﻿ Pregnancy Glossary


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  Abdomen (The Belly)

The body cavity below the chest that contains the stomach, liver, intestines and other organs.

Abdominal circumference (AC)

The distance around fetal abdomen.



Intentional or naturally occurring termination of pregnancy before the fetus is developed enough to survive.

See related terms

Abruptio placenta (Placental abruption)

Partial or complete separation of the placenta from the uterus before delivery. It happens  in  0.8-1.0% of all pregnancies and has a high recurrence rate. Contractions are usually present. Bleeding is also present in approximately 80% of patients. Factors that have been associated with abruption include maternal hypertension, intrauterine growth restriction (IUGR), non-vertex presentation, polyhydramnios, advanced maternal age, maternal smoking, cocaine use, chorioamnionitis, premature rupture of membranes, and blunt external maternal trauma


An acceleration is an abrupt increase in the fetal heart rate above baseline with onset to peak of the acceleration less than 30 seconds and less than 2 minutes in duration.


Shortening of the hands or feet

Active Labor

The active phase (active labor) of labor begins when the cervix is opened (dilated) to 6 cm in the presence of uterine contractions. During the active phase uterine contractions become more frequent, the cervix dilates more quickly, and the baby descends into the pelvis.

Acute Cervical Insufficiency

Cervical dilation of at least 2 cm with membranes visible at 16 0/7 to 22 6/7 weeks' gestation as used by Owen J et al.

Owen J, et al. Multicenter randomized trial of cerclage for preterm birth prevention in high-risk women with shortened midtrimester cervical length. Am J Obstet Gynecol. 2009 Oct;201(4):375.e1-8.PMID:19788970


Collective term for the placenta and fetal membranes that are delivered after the infant

Agenesis of the corpus callosum (ACC)

A birth defect in which there is partial or complete absence of the corpus callosum (the bundle of nerve fibers that connects the two hemispheres of the brain).  Read more...


Absence or lack of movement

Alloimmunization (Isoimmunization)

Production of an antibody against antigens produced by members of the same species.

Alpha-fetoprotein (AFP)

A protein produced by the fetal liver and yolk sac that can be detected in the mother's blood. Alpha-fetoprotein levels rise gradually throughout most of pregnancy and level off near term. High levels of alpha-fetoprotein are associated with a more advanced pregnancy than expected, multiple pregnancy, fetal death (including a vanished twin), an opening in the spine (spina bifida), an opening in the head (anencephaly), or an opening in the abdominal wall (gastroschisis).  Low levels may be associated with Down syndrome, trisomy 18, and some cases of Turner syndrome.


A procedure in which a needle is inserted into the uterus and a sample of the fluid surrounding the fetus is drawn out. The procedure may be done to evaluate the fetal chromosomes, to determine fetal lung maturity, or to obtain fluid to culture for possible infections. The procedure may also be performed to remove an excessive amount of amniotic fluid.


Infusion of fluid (usually normal saline or lactated Ringer's solution) into the amniotic cavity.

Amniotic fluid

Amniotic Fluid Index (AFI)

Amniotic fluid ‘sludge’

The sonographic finding of dense aggregates of particulate matter in the amniotic fluid close to the internal cervical os. Amniotic Fluid (AF) ‘sludge’ has been associated with microbial invasion of the amniotic cavity (MIAC), and histologic chorioamnionitis in patients with spontaneous preterm labor and intact membranes

Kusanovic JP, et al. Clinical significance of the presence of amniotic fluid 'sludge' in asymptomatic patients at high risk for spontaneous preterm delivery. Ultrasound Obstet Gynecol. 2007 Oct;30(5):706-14. PMID: 17712870

Amniotic sac

The membrane (amnion) that surrounds the fetus and the amniotic fluid.

Amniotic sheet

A 'shelf' in the amniotic cavity seen during ultrasound examination. Amniotic sheets represent chorion and amnion that has grown around uterine synechiae ( adhesions) .  Incomplete amniotic sheets  have a free edge. Complete amniotic sheets have no free edge, and have been associated with increased risk for intrauterine death.
Amniotic sheets may be mistaken for amniotic bands. However, amniotic bands more often appear as multiple thin membranes, and are  frequently attached to the fetus. Circumvallate placenta is another cause of uterine band, sheet, or shelf.

Tan KB, Tan TY, Tan JV, Yan YL, Yeo GS. The amniotic sheet: a truly benign condition?Ultrasound Obstet Gynecol. 2005 Nov;26(6):639-43.  PMID: 16254890

Amniotomy (artificial rupture of membranes , AROM)

A procedure performed (often using a plastic device that looks like a crochet needle ) to open the amniotic sac usually for the purpose of inducing or speeding up the progress of labor .


Decreased amount of normal hemoglobin in blood. Hemoglobin is the substance in red blood cells that carries oxygen.



A birth defect resulting in the absence of a major portion of the skull and brain. Anencephaly results when the upper portion of the neural tube fails to close. The condition is not compatible with life, and infants usually die within a few days after delivery.


Loss of sensation.

Angioedema, Hereditary

Angle of insonation

A measure of deviation from "straight on" to a reference plane measured in degrees. For example a Doppler ultrasound beam aligned to the flow of blood in a vessel has a zero degree of insonation to the flow. A Doppler ultrasound beam aligned perpendicular to the flow of blood in the same vessel has a 90 degree angle of insonation to the flow.


Malformation or abnormality.


Before birth.

Antenatal corticosteroids , ACS

Steroids (either betamethasone or dexamethasone) given to help the fetal lungs and other organs mature more rapidly. Antenatal steroids are given when preterm delivery is anticipated between 24 and 34 weeks' gestation with intact membranes, and at 24 to 32 weeks' with ruptured membranes.


Before delivery or birth.


In front

Antibody (Immunoglobulin)

Proteins secreted by white blood cells (lymphocytes) that bind to foreign molecules. Antibodies attach to the antigens and destroy the invader directly , or label them for removal by  white blood cells in thebody. Antibodies (immunoglobulins) are grouped into five classes or isotypes: IgG, IgA, IgM, IgD, and IgE.

A molecules that stimulates antibody production is called an antigen ( antibody generator). 

Anticardiolipin antibodies (ACA, aCL Antibody) *

An antibody that attaches to cardiolipin , a fatty molecule,  found mostly in the mitochondrial inner membrane where it is synthesized from phosphatidylglycerol  . ACA may be found in several diseases including antiphospholipid syndrome and systemic lupus erythematosus (SLE). Three classes of cardiolipin antibodies may be present in the blood: IgG, IgM and/or IgA.

Anti-c antibody (little c antibody) *

A protein made by the immune system that binds to a molecule called the c antigen found on the surface of red blood cells. The c antigen is part of the Rhesus blood group system which consists of several antigens (D , E , e , c, C, ). The antibody hastens removal of the c antigen (and the foreign blood cells) from the body.

Anti-c antibody is capable of crossing the placenta and causing anemia in the fetus and hemolytic disease of the newborn. Pregnancies complicated by anti-c antibody are managed as for Rh-D sensitization .

Anti-D antibody (Rh sensitization, Rh disease)*

A protein made by the immune system that binds to a molecule called the D antigen found on the surface of red blood cells. The D antigen is part of the Rhesus blood group system which consists of several antigens (D , E , e , c, C, ). The antibody hastens removal of the D antigen (and the foreign blood cells) from the body.

Anti-D antibody is capable of crossing the placenta and causing SEVERE anemia in the fetus and hemolytic disease of the newborn.

Anti-Duffy antibody (anti-Fya antibody)

A protein made by the immune system that binds to a molecule called the Fya antigen found on the surface of red blood cells. The Fya antigen is part of the Duffy blood group system which consists of the antigens Fya and Fyb . The antibody hastens removal of the and Fya antigen (and the foreign blood cells) from the body.

Anti-Fya antibody is capable of crossing the placenta and causing SEVERE anemia in the fetus and hemolytic disease of the newborn. Anti-Fyb has not been reported to cause significant hemolytic disease of the newborn.

Anti-Kell antibody

A protein made by the immune system that binds to a molecule called the Kell antigen found on red blood cells. The Kell antigen is part of the Kell blood group system which consists of several antigens ( Kell or K1 , Kpa, k  , Jsa  ,Jsb ). The antibody hastens removal of the Kell antigen (and the foreign blood cells) from the body.

Anti-Kell antibody is capable of crossing the placenta and causing SEVERE anemia in the fetus and hemolytic disease of the newborn.
SEE ALSO: Q & A ..a pregnant patient with anti-Kell antibodies...

Anti-Kidd antibody (anti-Jka  or anti-Jkb)

A protein made by the immune system that binds to a molecule called Kidd antigen found on the surface of red blood cells. The Kidd antigens Jk and Jkb are part of the Kidd blood group system.

Anti-Kidd antibody is capable of crossing the placenta and causing anemia in the fetus and hemolytic disease of the newborn.

Anti-Lewis antibody

A protein made by the immune system that binds to molecules called the Lewis antigens,  Le a and Le b. Lewis antigens are not made by the red blood cell, but are antigens present in body fluids and secretions that have been adsorbed onto the surface of the red blood cell. Lewis antigens are found in very low levels on the fetal red cells.

Most Lewis antibodies are of the IgM type and do not cross the placenta. Lewis blood group antibodies are not known to cause hemolytic disease of the newborn.

Anti-S antibody

A protein made by the immune system that bind to a molecule called the S antigen found on the surface of red blood cells. The S antigen is part of the MNS blood group system which consists of several antigens ( M, S,s, N)

Anti-S antibody is capable of crossing the placenta and causing anemia in the fetus and hemolytic disease of the newborn.

Apgar Score


Temporary cessation of breathing

Arcuate uterus

Midline thickening of the wall of the uterus at the uterine fundus (top of the uterus). The thickened area results from failure to completely dissolve the uterine septum during development. The arcuate uterus is considered to be a mild form of bicornuate uterus. An arcuate uterus does not appear to have an unfavorable effect on pregnancy.


The darker colored area around the nipple of the breast

Arnold-Chiari Malformation

A group of birth defects of the cerebellum (the part of the brain that controls balance) and base of the skull characterized by downward displacement of the cerebellum and related structures below the level of the foramen magnum (the large hole at the base of the skull).

Arrest of descent

Second-stage arrest may be diagnosed if there has been
"No progress (descent or rotation) for
4 hours or more in nulliparous women with an epidural
3 hours or more in nulliparous women without an epidural
3 hours or more in multiparous women with epidural
2 hours or more in multiparous women without an epidural"

Spong CY, et. al. Preventing the first cesarean delivery: summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, and American College of Obstetricians and Gynecologists Workshop. Obstet Gynecol. 2012 Nov;120(5):1181-93. doi http://10.1097/AOG.0b013e3182704880. PMID: 23090537

Arrest of dilatation

For spontaneous labor:
6 cm or greater dilation with membrane rupture AND 4 hours or more of adequate contractions (e.g., > 200 Montevideo units) OR
6 hours or more if contractions inadequate with no cervical change

For induced labor:
6 cm or greater dilation with membrane rupture or 5 cm or greater without membrane rupture AND 4 hours or more of adequate contractions (e.g., > 200 Montevideo units) OR
6 hours or more if contractions inadequate with no cervical change [4].


Artificial rupture of membranes (AROM)

See amniotomy.




To inhale into liquid or food into the lungs, or to draw (fluid) by suction

Augmentation of  labor

Stimulation the uterus to increase the frequency, duration , or strength of contractions when spontaneous contractions have failed to cause dilation or thinning (effacement) of the cervix leading to the delivery of the infant.

1. World Health Organization. Managing Complications in Pregnancy and Childbirth .A guide for midwives and doctors. 2003. http://who.int/reproductive-health/impac/Procedures/Induction_P17_P25.html ACOG Practice Bulletin No. 49.
2. American College of Obstetricians and Gynecologists. Dystocia and augmentation of labor.Obstet Gynecol 2003;102:1445–54.  

Autologous transfusion

"Infusion of  blood or blood component to the same individual from whom it was taken"

Autosomal dominant

A trait determined by a gene on any chromosome other than a sex chromosome (X or Y) that requires only one gene for the trait to be expressed. The chance of passing the trait to an offspring is at least 50% for each pregnancy.
 See Diagram

Autosomal recessive

A trait determined by a gene on any chromosome other than a sex chromosome (X or Y) that requires two genes for the trait to be expressed. A person with only one copy of the gene is said to be a carrier for the trait.
 See Diagram

Bag of waters

The membrane (amnion) surrounding the fetus and the amniotic fluid.

Bicornuate Uterus

Two separate single horn uterine bodies sharing one cervix. Bicornuate uterus is associated with increased risk for miscarriage, preterm labor, breech presentation, and fetal growth restriction.

Bishop Score

The Bishop Score (also known as Pelvic Score)  method used to rate the likelihood of a woman entering labor naturally in the near future.


The developmental stage of the fertilized egg about 5 days after fertilization before it implants into the lining of the uterus. It consists of a a liquid filled sphere with an outer layer of cells, the trophoblast, that will form the placenta  and an inner cell mass that forms the embryo.

Blighted Ovum

A fertilized egg that has failed to develop.

Blood pressure

Bloody show

Passage of blood-tinged mucus from the vagina caused by loss of the cervical mucous plug. Bloody show often precedes the onset of labor.

Body Mass Index (BMI)

The body mass index (BMI) is a measure of someone's weight in relation to their height. The BMI is used to estimate the amount of body fat a person has. The BMI is calculated either as:

BMI = (Weight in pounds / Height in inches 2 ) x 703

BMI = (Weight in kilograms / Height in meters 2)

Bradley Method (husband-coached birth)

A method of natural childbirth developed by Robert A. Bradley, M.D. (1917–98). The Bradley method emphasizes education and relaxation techniques for pain management. The method prepares the baby's father to be the mother's birth coach, and prepares the mother to deliver without pain medication.


In a fetus a mean heart rate less than 110 beats per minute lasting for at least two minutes. In an adult a sustained heart rate less than 60 beats per minute.

Braxton Hicks Contractions

Sporadic uterine contraction that do not increase in intensity and do not result in childbirth, typically felt after 20 weeks. Named after John Braxton Hicks a British gynecologist who first described these contractions in 1872.

Breech presentation

The baby is in a sitting position with the buttocks, knees, or feet nearest to the cervix.

Breech presentation occurs in 25 percent of pregnancies less than 28 weeks' and 1 to 3 percent of births at term. The three types of breech presentation are frank breech (flexed at hips with extended knees-legs above buttocks), footling breech (one or both hips extended-leg(s) extended below buttocks), and complete breech (flexed hips and knees-no limbs extended).


Bowing of the long bones

Caput succedaneum

Swelling and accumulation of fluid (edema) in the scalp of infants born vaginally. The swelling usually disappears within 24 to 48 hours.

Carpal Tunnel Syndrome (CTS)

Pain, numbness , and weakness of the hand and fingers caused by pinching of the median nerve as it passes through the space over the wrist (carpal) bones . Conditions associated with carpal tunnel syndrome include diabetes, hypothyroidism, arthritis, obesity, and pregnancy.


A hollow tube used to inject fluid into, or drain fluid from a space such as the bladder.


A collection of blood caused by rupture of blood vessels between the skull and the periosteum (the membrane surrounding a bone). The blood does not cross the joints of the skull, because it is trapped between the periosteum and bone. Subtle skull fractures may underlie a cephalhematoma. The condition generally resolves over several weeks.

Cephalic presentation

The fetal head is down near the mother's cervix.

Cephalic index

The ratio of the bi-parietal diameter (BPD) to the occipito-frontal diameter (OFD) X 100. The normal range is 70 to 86.  A cephalic index of less than 70 is considered dolichocephaly. An index of greater than 86 is considered to be brachycephalic




Cephalopelvic disproportion (CPD)

The fetal  head is too large to pass through the mother's pelvis. Cephalopelvic disproportion is usually diagnosed when labor fails to progress (cervical dilation and effacement have stopped) and is unresponsive to oxytocin augmentation.


A procedure used to temporarily stitch the cervix closed in pregnant women with a history of premature delivery caused by an incompetent cervix. Cerclage sutures are usually placed at 10 to 15 weeks' gestation

Cerebral Palsy

A group of disorders characterized by inability to move and /or to control movements caused by injury or abnormal development in the immature brain.

Certified nurse midwife (CNM)

A registered nurse with at least 1-2 years of nursing experience who has received additional training in delivering babies and providing prenatal and postpartum care to women. They are certified by the American College of Nurse-Midwives (ACNM).

Cervical os

The opening of the cervix

Cervical incompetence

Cervical insufficiency (sometimes called an incompetent cervix) is the failure of the cervix to maintain a pregnancy when there are no signs or symptoms of labor in the second trimester.

Cervical ripening

The process where the cervix becomes ready for labor by becoming softer , thinner and opening (dilating) during the last few weeks of pregnancy. Medications or mechanical dilators are sometimes used to artificially ripen the cervix before induction to make the cervix more favorable and a vaginal delivery more likely


Lower narrow part of the uterus that opens into the vagina.

Cesarean section (C-section)

An incision made through the abdomen and uterus for the purpose of delivering one or more fetuses. The incision on the abdomen may be vertical or transverse. The incision made on the uterus may not be in the same direction as the abdominal incision.

  • Low transverse (Kerr) See illustration
    • The most common incision. This incision is easy to repair and is associated with the lowest probability of rupture or dehiscence in a subsequent pregnancy
  • Low vertical (Kronig) See illustration
    • Used when lower uterine segment is undeveloped or for premature breech presentation.
  • Classical See illustration
    • This incision may be used when a back down transverse lie that cannot be converted to breech or cephalic presentation, inability to expose the lower uterine segment,  premature breech presentation, and anterior placenta previa.

Chadwick's sign

Bluish discoloration of the vaginal tissue and cervix  caused by accumulation of blood (venous congestion).  Chadwick's sign may be seen as early as six weeks of pregnancy.

CHARGE syndrome

A congenital disorder characterized by Coloboma, Heart defects, choanal Atresia, Retarded growth and development, Genital abnormalities, and Ear anomalies.

Lalani SR, Hefner MA, Belmont JW, et al. CHARGE Syndrome. 2006 Oct 2 [Updated 2012 Feb 2]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016. Available from: http://www.ncbi.nlm.nih.gov/books/NBK1117/

Chemical pregnancy

A positive pregnancy test ( elevated hCG level in the blood or urine) before pregnancy can be verified by ultrasound. Often used to refer to a pregnancy that has failed before reaching a size large enough to be seen on sonogram.

Chloasma (mask of pregnancy, melasma)

Blotchy areas of darkened skin over the the forehead, cheeks and upper lips associated with pregnancy or with the use of contraceptives. Exposure to ultraviolet (UV) rays from the sun or tanning salons intensifies the pigment changes. The areas of darkened skin usually fade several months after delivery or discontinuation of the contraceptive

Cholestasis of pregnancy (Intrahepatic cholestasis of pregnancy ,ICP)

A liver disorder in which the release of bile from the liver is thought to be blocked by high levels of the hormones estrogen and progesterone during pregnancy. The bile builds up in the blood causing itching. Cholestasis of pregnancy usually occurs in the second half of pregnancy, and affects about one in 200 pregnancies.


Inflammation of the fetal membranes and amniotic fluid usually associated with a bacterial infection. The bacteria responsible are usually those that are normally present in the vagina. The presence of fever, uterine tenderness, and foul vaginal discharge help to confirm the clinical diagnosis of chorioamniotis.


The outermost of the two fetal membranes that gives rise to the placenta.

Chorionic Villus Sampling (CVS)

Removal of cells that line the placenta, the chorionic villi, through the cervix using a catheter or through the abdomen using a needle. The material obtained may be tested for Down syndrome and other disorders. The procedure is usually performed between the 10th and 12th weeks of pregnancy .

Choroid plexus

Structures in the ventricles (spaces) of the brain that produce the cerebrospinal fluid. Each plexus is made up of a network of capillary blood vessels covered by transporting epithelial cells.

Choroid plexus cyst

Pockets of fluid in the choroid plexus believed to be caused by abnormal folding of the epithelium lining of the choroid plexus which traps fluid and debris .


Structures made of of tightly coiled DNA (deoxyribonucleic acid) found in the nucleus of a cell.
Chromosomes are the structures in the cells in the body that are inherited from each of parent, and hold the instructions for the  body looks and functions. Humans have 23 pairs of chromosomes for a total of 46. The first 22 chromosomes are numbered from largest to smallest in size. The 23rd pair are the sex chromosomes and are named as X or Y .

Chronic hypertension

High blood pressure present  before  pregnancy or detected before 20th week of pregnancy.

Circumvallate placenta Copyright © 2014 by Focus Information Technology.

Circumvallate placenta

The membranes insert closer to the center of the placenta instead of extending to the edge of the placenta  creating a folded and thickened placental margin that appears as a 'shelf-like' structure at  the placental edge during ultrasound examination. Circumvallate placenta has been associated with premature labor, stillbirth, hemorrhage and placental abruption

1. Suzuki S.Clinical significance of pregnancies with circumvallate placenta.J Obstet Gynaecol Res. 2008 Feb;34(1):51-4. PMID: 18226129
2. Harris RD, et al. Accuracy of prenatal sonography for detecting circumvallate placenta. AJR Am J Roentgenol. 1997 Jun;168(6):1603-8. PMID: 9168736

Cleft lip and palate (orofacial cleft)

A gap of the lip or lip and palate (roof of the mouth) caused by failure of the lip or the lip and palate to grow together. The lip and primary palate close during the 4th to 7th weeks of gestation. The secondary palate begins to close the 6th week and is completed between the 9th and 12th weeks of gestation. Cleft lips are unilateral or bilateral. See Image

Club foot (Talipes equinovarus)

The foot is turned inward. Both feet are affected in 50% of cases. The defect may be corrected surgically. Club foot occurs in about 1 in 700 to 800 births. In a small number of cases, clubfoot may be seen in association with spina bifida or as part of a skeletal dysplasia. The estimated risk of recurrence in future children is 3 to 8% if 1 child is affected and 10% if 1 child and 1 parent are affected.


Thin, yellow, milky fluid secreted by the breasts in the last weeks of pregnancy and the first few days after delivery. Colostrum contains high levels of maternal antibodies.


Enlargement of the occipital horns of the lateral ventricles in the brain.

Congenital Pulmonary Airway Malformation (CPAM ) , Congenital Cystic Adenomatoid Malformation (CCAM)

An abnormally formed piece of lung made up of closed sacs (cysts) that will never function as normal lung tissue . A CPAM usually involves only one lobe of a lung. We do not know what causes CPAM, but CPAM occurs in about 1 in 10,000 fetuses. CPAM was previously called congenital cystic adenomatoid malformation (CCAM).

On ultrasound examination a CPAM may appear macrocystic, microcystic, or a mixture of the two. A macrocystic CPAM has one or more large cysts (>= 5mm) that appear as empty spaces or holes in the lung . A microcystic CPAM has very small cysts (< 5mm ) giving it the appearance of a solid well-defined mass that is brighter (more white) than the surrounding normal lung.


To be related through a recent common ancestor ( a close blood relative ).

Contraction, uterine

Tightening of the muscular wall of the uterus that may feel like menstrual cramps.

Cord compression, Umbilical cord compression

Squeezing or pinching of the umbilical cord . Umbilical cord compression may interrupt blood flow to the fetus causing the fetal heart rate to decrease .  Decreased  heart rate for a brief time (variable deceleration) may also be seen with  head compression and with movement in the premature fetus.

Sorokin Y, et. al., The association between fetal heart rate patterns and fetal movements in pregnancies between 20 and 30 weeks' gestation. Am J Obstet Gynecol. 1982 Jun 1;143(3):243-9. PMID: 7081342

Corpus luteum (CL)

A yellow colored structure that the develops from cells of the empty egg follicle after the egg is released. The corpus luteum secretes progesterone which prepares the lining of the uterus for implantation by the embryo.


Premature closing of joints or sutures in the skull. Craniosynostosis may occur as an isolated finding or may be associated with a syndrome such as Apert, Chotzen, Pfeiffer, Carpenter, and Crouzon syndromes


The appearance of the infant's scalp at the vaginal opening during labor.

Crown-rump length (CRL)

The distance between the top of the head (crown) and buttocks (rump) of the embryo or fetus.

Cystic fibrosis

A condition characterized by  thick mucus build up in the lungs and digestive tract. The mucus in the lungs causes inflammation and infections leading to the formation of scar tissue (fibrosis) and cysts in the lungs. Cystic fibrosis (CF) also affects the pancreas, liver, intestines, sinuses, and sex organs

Cystic hygroma

Single or multiple sac-like structures caused by abnormal development of the lymphatic system (the system responsible for carrying white blood cells that help fight infection and disease). Cystic hygromas occur most often about the neck. More than half of fetuses with cystic hygromas diagnosed in utero have Turner syndrome (one x chromosome). Image 1    Image 2

Cytomegalovirus (CMV) infection

Cytomegalovirus (CMV) is a common virus transmitted by direct person-to-person contact through saliva, breast milk, or urine. About 33% of (33 of every 100) women who become infected with CMV for the first time during pregnancy pass the virus to their fetuses. Severe infections can lead to significant damage to the nervous system and other vital organs of the unborn baby.

Findings on ultrasound that would raise the possibility of a severe CMV infection include very high or very low levels of amniotic fluid , fluid collections in the abdomen (ascites), dense appearing (echogenic) bowel, growth restriction, very small head (microcephaly), dilation of the fluid filled chambers of the brain ventriculomegaly or hydrocephaly), or calcium deposits in the brain or liver.

Deep vein thrombosis, DVT

A blood clot in a blood vessel that carries blood back to the heart (vein). Symptoms include pain, tenderness, and swelling of the affected extremity.


A condition in which a person has an abnormally high amount of sugar (glucose) in their blood. Diabetes occurs when the body does not produce insulin, the substance in the body that lowers blood sugar, or the cells in the body do not respond to insulin .

Diabetic Ketoacidosis(DKA)

A condition that occurs in diabetics due to lack of insulin. Signs and symptoms may include nausea, vomiting, abdominal pain, thirst, excessive urine output, dehydration fast pulse, and low blood pressure .  Without treatment DKA progresses to coma and death. Read more...


Two separate amniotic sacs (bags of water)

Diaphragmatic hernia (congenital diaphragmatic hernia -CDH)

An abnormal opening in the diaphragm (the muscle used for breathing . It divides the chest from the abdomen.) caused by failure to completely form the diaphragm. The defect allows the abdominal organs to move into the chest cavity which may prevent normal development of the lungs. The condition is associated with a 30 to 60% death rate due to underdeveloped lungs and associated abnormalities such as heart defects, malformed or absent kidneys, and hydrocephalus. The presence of the liver in the chest generally increases the likelihood of a poor outcome.


Two separate placentas.

Dilation and curettage (D and C)

A surgical procedure in which the cervix is gradually opened with instruments called dilators and the surface of the endometrium (lining of the uterus) is scraped away with a curette, a sharp-edged instrument.

Down syndrome (trisomy 21)

A disorder characterized by mental retardation, flat facial profile with protruding tongue, poor muscle tone, excess skin on neck, slanting eye openings (slanted palpebral fissures), abnormal pelvis, and short stature. In addition there may be heart defects (AV canal defect) , gastrointestinal malformations, problems with vision and hearing, and increased susceptibility to leukemia and infections. The syndrome is named after John Langdon Down, the first physician to identify the syndrome.

Down syndrome occurs in one out of 800 live births and is caused by extra material from chromosome 21. In most cases (95%) there are three copies of chromosome 21 instead of two. In 90% of these cases the extra chromosome is inherited from the mother.

Due date (estimated due date-EDD)

The date that spontaneous onset of labor is expected to occur. The due date may be estimated by adding 280 days  to the first day of the last menstrual period (LMP).


Slow or difficult labor caused by inadequate uterine contractions, abnormalities in the maternal pelvis, a large fetus or a combination of these causes.

Doppler ultrasound

A method using ultrasound to detect and measure blood flow.

Echogenic (hyperechogenic) bowel

Intestine that reflects more sound on an ultrasound examination than usual making it appear very white. The finding of echogenic bowel may be a normal variant in some babies. However, the finding of echogenic bowel has been associated with an increased risk for chromosomal abnormality (such as Down syndrome) , cystic fibrosis, viral infection (CMV and parvovirus) , unexplained fetal death, growth restriction, and premature birth.

Echogenic focus

A distinct area that reflects more sound on an ultrasound examination than usual making it appear very white. The term commonly refers to bright spots seen in the ventricles of the heart. Very bright small spots may represent dense papillary muscles or tendons within the heart. Cardiac tumors may also appear as spots within the heart . However, tumors tend to be larger, multiple, and are not as bright as an echogenic focus.


New-onset convulsions (grand mal seizure) in a woman with preeclampsia. Preeclampsia is a condition characterized by high blood pressure and protein in the urine that develops after the 20th week of pregnancy. The cause of preeclampsia is unknown.

Ectopic pregnancy

A pregnancy growing outside of the uterus.


Swelling caused by the accumulation of fluid under the skin.

Edwards' syndrome (Trisomy 18)

A rare disorder that happens when the baby has three copies of chromosome 18 instead of the usual 2 copies. Chromosomes are the structures in the cells of your body that are inherited from each of your parents.  Babies with trisomy 18 have severe mental retardation and usually have many birth defects, because of the extra chromosome 18. Only 5% to 10 % of infants survive the first year after delivery. Death is usually caused by inability to maintain normal breathing or heart and lung problems Ultrasound findings that are often seen in babies with trisomy 18 include cleft lip and palate, a small jaw, low set ears, club feet, clenched fists, a single umbilical artery , kidney abnormalities, poor growth, and a high level of amniotic fluid (polyhydramnios) . More than 90% of babies with trisomy 18 will have a heart defect.


Thinning or shortening of the cervix


A fertilized egg from initial cell division until the eighth week of development.


A defect affecting the skull resulting in the herniation of the meninges and portions of the brain through a bony midline defect in the skull


A method of pain relief in which anesthesia is injected into the space around the spinal cord (epidural space)


An incision made between the vagina and rectum to widen the vaginal opening for delivery.

Erythema infectiosum (Parvovirus infection)

Erythema infectiosum also known as Fifth disease is a common childhood illness caused by a virus called parvovirus B19. About 50% of all adults have been infected sometime during childhood or adolescence.  Women who become infected with parvovirus for the first time during their pregnancy may pass the virus to their unborn child. Parvovirus can cause severe anemia in the fetus which may lead to congestive heart failure. The heart itself may become enlarged. In addition parvovirus infection has uncommonly been associated with enlarged ventricles in the fetal brain and calcium deposits in the spleen.

External cephalic version

To manually turn the fetus from a breech (sitting position) presentation to a cephalic presentation (head down nearest to the cervix) by applying external pressure on the mother's abdomen.

Extremely low birth weight (ELBW)

A birth weight of less than 1000 grams ( 2 pounds 3 ounces)

Factor V

Factor V is  a protein in the blood that promotes clotting of the blood by accelerating the activation of prothrombin to thrombin. Activated factor V is inactivated by activated protein C. Factor V is broken down by activated protein C (APC) which acts to control the formation of the clots.

Factor V Leiden is a form of factor V that is resistant to APC . People with factor V Leiden have an increased tendency to form blood clots (thrombophilia)

Factor V Leiden Mutation (activated protein C resistance)

A genetic mutation in the factor V gene that makes the activated factor V protein resistant to inactivation by protein C. The increased activity of factor V in the blood leads to a higher risk of forming a blood clot (thrombophilia) . The factor V Leiden mutation has a prevalence of 5–9% in the general population.

Failed Induction of Labor

"Failure to generate regular (e.g. every 3 minutes) contractions and cervical change after at least 24 hours of oxytocin administration, with artificial membrane rupture if feasible. "

Spong CY, et. al., Preventing the first cesarean delivery: summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development, Society for Maternal-Fetal Medicine, and American College of Obstetricians and Gynecologists Workshop. Obstet Gynecol. 2012 Nov;120(5):1181-93. doi: http://10.1097/AOG.0b013e3182704880. PMID: 23090537

Failure to progress, prolonged labor


Fetal fibronectin (fFN)

Fetal fibronectin (fFN) is a substance that acts like "glue" holding the fetal sac to the uterine lining during pregnancy. It can normally be found in the cervicovaginal secretions of women up to 22 weeks of gestation.  However, the presence of fetal fibronectin in cervicovaginal secretions between 24 and 34 completed weeks of gestation is reported to be associated with preterm delivery.


A human conceptus from 70 days' gestational age until delivery

Fetal viability

The capacity for sustained survival outside the uterus as determined by the judgment of the responsible attending physician.  Newborns with malformations incompatible with life such as renal agenesis, anencephaly, trisomy 13 , or trisomy 18 are not considered viable regardless of the gestational age.

Fetal Warfarin Syndrome

A group of birth defects associated with exposure of the developing fetus to warfarin (Coumadin®) an oral anticoagulant used to prevent blood clots. The defects include nasal hypoplasia, stippled epiphyses, limb deformities, mental retardation, and seizures. Hall et al.  placed the critical period for warfarin effects on the fetus as 6 to 9 weeks following conception.

Hall JG , et al. Maternal and fetal sequelae of anticoagulation during pregnancy.Am J Med. 1980 ;68:122-40. PMID: 6985765

Fibroid (leiomyoma, myoma)

A non-cancerous (benign) growth of fibrous tissue and muscle fibers. Fibroids are often found in the uterus, and occur in about 30% of women over the age of 30.

Fluorescence in situ hybridization, FISH

A technique used for identifying a specific DNA sequence on a chromosome. The technique uses single-stranded DNA segments attached to a fluorescent (glowing) dye, called a probe. The probe is mixed with the test chromosomes and sticks to its corresponding sequence (the DNA sequence being tested for)  on the chromosome.

Follicle stimulating hormone (FSH)

 A hormone (a chemical) produced by the pituitary gland in the brain that stimulates the growth of eggs in the ovaries and the production of sperm in the testes. An elevated FSH suggests partial or complete ovarian failure.

Fontanel ("soft spot")

A membranous gap between the bones of the developing skull.
The newborn normally has six fontanels the anterior, posterior, two mastoid, and two sphenoid fontanels. The most prominent fontanel is the diamond-shaped anterior fontanel which is closed in 96 percent of infants by 24 months of age.

Fragile X Syndrome (Martin-Bell syndrome)

A disorder affecting males and females characterized by mental retardation.. In the U.S. fragile X syndrome affects approximately 1 in 4000 males and 1 in 8000 females and is a common cause of autistic-like behaviors.  Fragile X syndrome is caused by an expansion mutation that prevents the normal expression of the the Fragile X mental retardation 1 (FMR1) gene located on the X chromosome.

Fraternal twins (dizygotic twins)

Two offspring created when two separate eggs are fertilized by separate sperm during the same menstrual cycle. The two products of conception develop as two separate embryos, and each embryo develops its own membranes and placenta.

Fundal height

The distance from the top of the pubic bone to the top of the pregnant uterus (fundus) in centimeters. The measurement is used to approximate fetal age and growth.


The uppermost part of the uterus.


Gastroschisis is a birth defect in which the baby's intestines (bowels) stick out through a hole to one side of the belly button.

Gastroschisis is thought to arise from disruption of blood flow to the affected abdominal wall. Another explanation is that  the yolk sac does not become part of the the umbilical cord, as it normally does, leaving a hole about 2 to 4 centimeters (0.8 to 1.6 inches) wide that is nearly always to the right side of the belly button.

A section of the molecule DNA (deoxyribonucleic acid) which codes for a particular protein and carries the hereditary information for such characteristics as hair color, eye color, and susceptibility to disease.

Genetic counseling
Evaluation of prospective parents' risks of having a child born with a birth defect or genetic disorder, and advise on their options for testing and treatment.

Gestational age

The time elapsed since the first day of the last menstrual period. If pregnancy was achieved using assisted reproductive technology, gestational age is calculated by adding 2 weeks to the conceptional age.

Gestational diabetes (GDM)

Gestational diabetes mellitus (GDM) is diabetes that is found for the first time when a woman is pregnant. The high blood sugar in gestational diabetes appears to be caused by hormones produced by the placenta that prevent the mother's cells from responding to her insulin. It is estimated that gestational diabetes affects about 18% of pregnancies.

Gestational hypertension

High blood pressure occurring for the first time after 20 weeks gestational age
 A systolic blood pressure (SBP) greater than or equal to 140 mm Hg OR
 a diastolic blood pressure (DBP) greater than or equal to 90 mm Hg on at least two occasions at least 4 hours apart

 The American College of Obstetricians and Gynecologists. Task Force on Hypertension in Pregnancy Hypertension in Pregnancy. Hypertension, Pregnancy Induced --Practice Guideline wq244 2013 http://www.acog.org/~/media/Task%20Force%20and%20Work%20Group%20Reports/


A pregnant woman.

Group B streptococcus:

Group B streptococcus (GBS) is a bacteria normally found in the vagina and/or rectum of about 1 in 4 of all healthy women. GBS bacteria passed from the mother to the baby can cause some babies to become very sick and even die.

Hegar's sign

Softening of the lower uterine segment just above the cervix seen as a probable sign of pregnancy. Originally described by the German gynecologist Ernst Ludwig Alfred Hegar; Hegar's sign may be observed as early as six weeks of pregnancy.

HELLP syndrome

HELLP is an acronym that describes the syndrome of :  H Hemolysis; EL elevated liver enzymes; LP, low platelets.

HELLP syndrome usually presents in the third trimester with right upper quadrant or epigastric pain, nausea, and vomiting. HELLP syndrome is considered to be a variant of preeclampsia.  HELLP syndrome occurs in approximately 0.2 to 0.6 percent of all pregnancies. The cause of HELLP syndrome is unknown.

Strict criteria for the diagnosis of HELLP syndrome:

  • Hemolysis (characteristic peripheral blood smear) and serum lactate dehydrogenase levels >600 U/L
  • Serum aspartate aminotransferase levels >70 U/L
  • Platelet count <100,000/mul.

Hemolytic disease of the newborn (HDN)
Anemia in a newborn infant caused by the destruction of red blood cells. In severe cases jaundice, pallor, an enlarged spleen, or hydrops may be present


A group of hereditary disorders characterized by prolonged bleeding and sometimes excessive bleeding. Read more...

Hepatitis B

Hepatitis C 

Hepatitis C virus (HCV) is a single-stranded RNA virus . Injecting-drug use currently accounts for 60% of HCV transmission in the United States. Blood transfusion, is an uncommon cause of recently acquired infections . Sexual transmission of HCV appears to be inefficient relative to hepatitis B virus (HBV). Transmission between sexual partners of persons with chronic HCV infection with no other risk factors for infection is about 5% (range, 0% to 15%) . Approximately 7-8% of hepatitis C virus-positive women transmit hepatitis C virus to their offspring with a higher rate of transmission seen in women coinfected with HIV . In one small study acute maternal hepatitis appears to have no effect on the incidence of congenital malformations, stillbirths, abortions, or intrauterine malnutrition. However, acute hepatitis may increase the incidence of prematurity. Pregnancy does not appear to be adversely affected by chronic HCV.

Hydrocephaly (hydrocephalus, water on the brain)

Enlargement of the spaces within the brain (ventricles ) caused by excessive fluid (cerebrospinal fluid). The excessive fluid may cause enlargement of the infant's head.
The abnormally increased fluid may be the result of increased production of fluid, but more commonly is caused by obstruction of fluid flow between the different spaces in the brain. Hydrocephaly has been associated with aqueductal stenosis, spina bifida, X-linked hydrocephalus, Arnold-Chiari malformation , Dandy-Walker malformation,agesnesis of the corpus callosum ,  tumors, subarachnoid hemorrhage, infections (CMV and toxoplasmosis) , and chromosome abnormalities


Enlargement of the renal pelvis (the part of the kidney that collects urine) to greater than 10 mm.  Renal pelvis dilation of 4 to 10 mm in anterioposterior diameter is commonly referred to as fetal pyelectasis. Hydronephrosis is usually caused by a blockage of the flow of urine along the urinary tract.


Hydrops fetalis is a condition in the fetus characterized by an abnormal collection of fluid with at least two of the following:

  • Edema (fluid beneath the skin, more than 5 mm).
  • Ascites (fluid in abdomen)
  • Pleural effusion (fluid in the pleural cavity, the fluid-filled space that surrounds the lungs)
  • Pericardial effusion (fluid in the pericardial sac, covering that surrounds the heart)



High blood pressure . A systolic blood pressure (SBP) greater than or equal to 140 mm Hg OR a diastolic blood pressure (DBP) greater than or equal to 90 mm Hg or both


See also Blood pressure

Identical twins (monozygotic twins)

Two offspring created when a single fertilized egg divides to form two separate embryos during the first 2 weeks after conception. Identical twins account for about 30% of naturally occurring twins in the United States.

Implantation (nidation)

Penetration into the womb by the embryo. Implantation occurs approximately 6 days after conception.

Implantation Bleeding

Bleeding that occurs when the fertilized egg attaches to the uterus (womb) is called implantation bleeding. Implantation bleeding is common and may be mistaken for a menstrual period. The bleeding usually lasts for 1 to 2 days.

Incompetent Cervix

See cervical incompetence

Induction of labor

Stimulation of uterine contractions before the spontaneous onset of labor in order to achieve a vaginal delivery.


A child under one year of age.


Inability to conceive after one full year of regular sexual intercourse without the use of contraception.

Intracytoplasmic sperm injection, ICSI

A procedure in which a single sperm is injected directly into an egg . It is used in couples with infertility due to male factor infertility such as low sperm count or low sperm motility .

Intrauterine fetal death

A fetus with a crown-rump length more than 15 mm long without cardiac activity.

Intrauterine insemination, IUI

A procedure in which washed sperm, in high concentration,  is placed inside a woman's uterus around the time of ovulation to facilitate fertilization. It may be used in couples with infertility due to cervical factor or mild male factor infertility.


In utero

Inside the uterus (womb).


A chromosomal rearrangement in which a segment of the chromosome breaks away from the chromosome and re-inserts into the chromosome 180 degrees relative to its previous orientation. See more...

In vitro fertilization , IVF

A process in which an egg is fertilized by sperm outside the body in a laboratory. Used in couples with infertility due to damaged or absent fallopian tubes , unexplained infertility, ovulation disorders, and male factor infertility such as decreased sperm count .


A chromosome with two identical arms due to abnormal division of the chromosome in the transverse plane instead of longitudinally.


Yellowing of the skin, eyes, and membranes caused by too much bilirubin in the blood. Bilirubin is a yellowish pigment produced from the breakdown of red blood cells. Bilirubin is removed from the body largely by the liver. The mild jaundice that commonly occurs between the 2nd and 5th day of life in newborns is called physiological jaundice and is due to the newborn's immature liver function.


A picture of an individual's chromosomes. The 23 pairs of chromosomes are organized according to size, location of the centromere, and the pattern of bands on each chromosome. See picture

Kegel exercises (pelvic floor muscle exercises)

An exercise performed to improve bladder control developed by Dr Arnold Kegel. The exercises are carried out by repeatedly tightening and releasing the pubococcygeal and levator ani muscles pelvic muscles (those muscles used to stop the flow of urine).

Kell blood antibody (Anti-Kell)

A protein made by the body's immune system that attaches to a molecule called the Kell antigen found on some peoples red blood cells. The Kell antigen is part of the Kell blood group system which consists of several antigens ( Kell or K1 , Kpa, k , Jsa ,Jsb ). The antibody hastens removal of the Kell antigen (and the foreign blood cells) from the body.


 Rh (anti-D, anti-E, anti-c ), Kell (anti--K), Duffy (anti-Fya) antibodies are the most likely to cause hemolytic disease of the fetus and newborn (HDFN) requiring a blood transfusion.


A condition characterized by athetoid cerebral palsy, hearing loss, vision abnormalities, and dental problems. Kernicterus is caused by very high levels of bilirubin in the newborn.


Regular contractions of the uterus that cause dilatation and thinning (effacement) of the cervix leading to the delivery of the infant.


The folds of skin at the opening of the vagina consisting of large outer folds called the labia majora and inner folds called the labia minora.

Laceration ( Tear )

A cut or tear in tissues. Spontaneous lacerations of the perineum (the area between the vagina and anus) may occur as a result of childbirth. Perineal lacerations are classified by degree.


The production and excretion of milk by the breast.

Lamaze (Lamaze method)

 A method of childbirth preparation using behavioral techniques to reduce pain and anxiety in labor developed by the obstetrician Ferdinand Lamaze (1891-1957).


The fine hair that covers the fetus.

Leopold's maneuvers

4 specific steps in palpating the uterus through the abdomen in order to determine the lie and presentation of the fetus.


The longitudinal axis of the fetus in relation to the mother's longitudinal axis (i.e., longitudinal would be parallel to the mother).

L&D (L and D)

Labor and Delivery.

Lightening (dropping, engagement)

The descent of the presenting part of the fetus into the pelvis.


Last menstrual period. Refers to date of the start of the last menstrual period.

Low-lying placenta

The edge of the placenta is less than 2 centimeters from the opening of the cervix (internal os) but does not cover the internal opening of the cervix.


Growth beyond a specific weight, usually 4,000 grams  (8 pounds 13 ounces) or 4,500 grams (9 pounds 15 ounces)  regardless of the gestational age

REFERENCE:  Fetal Macrosomia Number 22, November 2000 (Reaffirmed 2015) American College of Obstetricians and Gynecologists Obstet Gynecol.


Magnesium sulfate

A naturally occurring mineral used to prevent and treat seizures in preeclampsia - eclampsia.

Mask of pregnancy (melasma)

See chloasma


Inflammation of the breast, usually caused by infection in a woman who is breast-feeding or has recently delivered.  The condition is treated with antibiotics, and the mother may continue to breast feed while being treated.

Maternal Mortality Ratio

Mean corpuscular volume (MCV)

The average red blood cell size expressed in femtoliters (fl). One femtoliter (fL) = 10-15L = 1 cubic micrometer (μm3).


The thick, mucoid, dark green contents of the fetal intestine.

Meconium Aspiration Syndrome (MAS)

Respiratory distress in an infant born through meconium-stained amniotic fluid (MSAF) whose symptoms cannot be otherwise explained

Fanaroff AA.Meconium aspiration syndrome: historical aspects. J Perinatol. 2008 Dec;28 Suppl 3:S3-7. doi: 10.1038/jp.2008.162. PMID: 19057607


An abnormally small head defined as a head circumference of 3 standard deviations or more below the mean for the gestational age. Read more...


An abnormally small jaw (mandible).
Micrognathia may occur as an isolated finding or may be found in association with many syndromes including trisomy 18, Treacher-Collins syndrome, Pierre Robin syndrome, Russell-Silver syndrome , Seckel syndrome, Progeria, and Smith-Lemli-Opitz syndrome


Shortening of all the long bones (humerus, radius, ulna, femur, tibia, and fibula) of the extremities.  Micromelia is a characteristic of many forms of skeletal dysplasias including, thanatophoric dysplasia, homozygous achondroplasia, osteogenesis imperfecta Type II and III, achondrogenesis, diastrophic dysplasia, short rib polydactyly syndrome, Chondroectodermal dysplasia, Campomelic dysplasia, Kniest dysplasia, dyssegmental dysplasia, hypophosphatasia (perinatal lethal).


A person who provides pregnancy, birth and postnatal support for normal births.

Milia (milk spots)

Tiny, 1 to 2 mm, white bumps (nodules) found on the face and nose of newborn infants. The bumps usually disappear within a few weeks of delivery without treatment.

Miscarriage (spontaneous abortion, SAB)

A pregnancy loss before 20 weeks' gestation calculated from the date of onset of the last menses. Up to 20 % of all recognized pregnancies end in miscarriage with 80% occurring during the first trimester.
The risk of miscarriage recurring in a woman with no live births after one miscarriage appears to be approximately 13 %, after two prior miscarriages 25%, and after three miscarriages 50%. However, if she has had a least one live birth the risk having another miscarriage after 3 prior miscarriages is 30%.

Stenchever MA, Droegemueller W, eds. Comprehensive Gynecology. 4th ed. St. Louis: Mosby, 2001p. 413-415

Molding (moulding)

Abnormal shape of a baby’s head caused by pressure on the head during childbirth

Mongolian spot

A bluish-gray birthmark over the lower back and rump of infants that may be mistaken for bruising. Mongolian spots are most commonly seen in infants of African, Asian, Hispanic, and Native American descent. They are harmless and most will have completely faded by the age five.


One amniotic sac (bag of water)


One placenta

Monozygotic twins (identical twins)

Two separate embryos conceived from a single fertilized egg. Identical twins account for about 30% of naturally occurring twins in the United States

Mucus plug (cervical mucus plug)

An accumulation of thick clear secretions in the cervical canal.


A woman who has been pregnant more than once regardless of whether she carried the pregnancy to term.


A woman who has given birth to an infant at least once before. A multiple gestation counts as a single birth.

Myelomeningocele (meningomyelocele , spina bifida cystica)

A birth defect in which the spinal cord and the membranes covering the spinal cord (meninges) protrude through a cleft in the bones of the spine (vertebrae) usually in the lower back or tailbone (lumbosacral) region. Myelomeningocele is a form of spina bifida that typically results in paralysis and loss of sensation below the level of the spinal defect.

Natural childbirth

Labor and childbirth with minimal or no medical intervention including drugs to relieve pain.

Neonatal intensive care unit (NICU, newborn intensive care unit)

An intensive care unit that cares for high risk newborn babies


A newborn infant until 28 days of age.


A physician who has completed specialty training in pediatrics and additional subspecialty training in the care of newborns that are ill or require special medical care

Necrotizing Enterocolitis (NEC)

An inflammatory disease of the bowel (enterocolitis) usually seen in premature infants. Injured bowel may die (necrosis) and allow the intestinal contents to leak into the abdominal cavity causing severe infection which can be fatal.

Neural-tube defect (NTD)

A general term for birth defects caused by incomplete closure of the tube shaped structure (neural tube) that forms the brain and spinal cord.   Failure of the cranial end to close results in lack of a complete brain (anencephaly) . Failure of the caudal end ,near the rump,  to close results in an open spinal cord (spina bifida).

Neural tube defects mat be seen using ultrasound , and usually cause  serum alpha-fetoprotein levels to be elevated  in the mother's blood .


A  pigmented area of the skin. For example, a mole or birthmark.

Nonstress Test (NST)

A method for testing fetal well-being. The study is performed by making a graphical recording of the fetal heart rate using an electronic monitor.




Abnormally low amount of amniotic fluid. Quantitatively an amniotic fluid index (AFI) of 5 or less or the largest vertical pocket of amniotic fluid volume is 2 or less .Causes of oligohydramnios may include ruptured membranes (water bag), urinary tract abnormalities , fetal growth restriction, and postmaturity.

Oxytocin (Pitocin)


Ovarian cyst





Release of an egg (ovum) from its follicle in the ovary .


A birth defect of the abdominal wall that allows the bowel and /or liver to protrude into the base of the umbilical cord (a type of hernia). Omphalocele occurs in approximately 1 in 4,000 births.  Congenital syndromes that have been associated with omphalocele include trisomy 18, trisomy 13, triploidy, Turner syndrome, Beckwith-Wiedemann syndrome,Pentalolgy of cantrell, and OEIS complex. The outcome for omphalocele is generally good if the chromosomes are normal and there are no other abnormalities

Pap smear (Papanicolaou smear)

A screening method for cervical cancer named after George Papanicolaou (1883-1962),

Para, Parity

The number of completed pregnancies beyond 20 weeks gestation (whether viable or nonviable). The number of fetuses delivered does not determine the parity. For example a woman who has been pregnant once and delivered twins at 38 weeks would be noted as Gravid 1 Para 1.

Cunningham FG. ed Williams Obstetrics, 22nd ed., New York: McGraw-Hill.2005
Mark Morgan and Sam Siddighi. NMS Obstetrics and Gynecology (National Medical Series for Independent Study).2004 p 45

Patent Ductus Arteriosus (PDA)

Failure of the blood vessel (called the ductus arteriosus) to close after birth. The ductus arteriosus is a normal structure in the fetus that diverts blood from the fetal lungs by connecting the pulmonary artery directly to the ascending aorta.


A physician who has completed specialty training in the development, care and diseases of children.


The lower part of the abdomen, between the hip bones that contains the uterus, bladder , and part of the large intestine

Percutaneous umbilical blood sampling (PUBS)

A procedure in which a needle is inserted into the uterus and into the umbilical cord of the fetus at the base of the placenta. A sample of fetal blood is then withdrawn.


Around the time of birth. As defined by the World Health Organization (WHO) ICD-10 the perinatal period is begins at " 22 completed weeks (154 days) of gestation (the time when birthweight is normally 500 grams) and ends seven completed days after birth".


A physician who has completed specialty training in obstetrics and gynecology and additional subspecialty training in high risk pregnancy and disorders of the fetus. Also called a maternal-fetal medicine specialist.

Pfannenstiel's incision (Bikini incision)

A horizontal cut made through the skin just above the joint of the pubic bones.

Placenta (Afterbirth)

A disk-shaped organ that develops during pregnancy. The placenta is attached to the uterus on one side by its large flat surface and to the fetus by the umbilical cord on its other side. The placenta exchanges nutrients, wastes, and gases between the blood of the mother and fetus as well as producing numerous hormones. Normally the placenta is delivered after the birth of the infant.

Placenta Accreta, Increta, Percreta

Abnormal penetration of the placenta beyond the lining of the uterus to varying depths.

  • Placenta accreta. The placenta adheres directly to the myometrium (muscular wall of the uterus)
  • Placenta increta. The placenta grows into the myometrium.
  • Placenta percreta. The placenta grows completely through the myometrium.


    Placental insufficiency

    Failure or inability of the placenta to normally exchange nutrients, wastes, and gases between the blood of the mother and fetus.

    Giles WB, et al .,Fetal umbilical artery flow velocity waveforms and placental resistance: pathological correlation. Br J Obstet Gynaecol. 1985 Jan;92(1):31-8. PMID: 3966988
    Baschat AA, Weiner CP.Umbilical artery doppler screening for detection of the small fetus in need of antepartum surveillance. Am J Obstet Gynecol. 2000 Jan;182(1 Pt 1):154-8.PMID: 10649171


    Placenta Previa

    A condition in which the placenta (including the marginal veins) partially or completely covers the opening of the cervix .


    Placental lakes (placental vascular lacunae, placental caverns, placental venous lakes, placental sonolucencies)

    Placental lakes are enlarged spaces in the placenta filled with maternal blood called also called intervillous vascular spaces.

    Placental villi

    Finger-like projections of the placenta that contain fetal blood vessels. The villi are surrounded by spaces containing maternal blood (intervillous space).

    Pleural effusion

    Polyhydramnios (too much amniotic fluid)

    An abnormally high amount of amniotic fluid. Quantitatively an amniotic fluid index (AFI) of 24 or more, or the largest vertical pocket of amniotic fluid volume is 8 cm or more . Some causes of polyhydramnios  include  gastrointestinal abnormalities (such as esophageal atresia and  intestinal obstruction), central nervous system abnormalities, chromosomal abnormalities, nonimmune hydrops skeletal dysplasias diabetes twin- to -twin transfusion. Many times no cause is found. See also Amniotic fluid...

    Ponderal Index


    Following birth.

    Postpartum blues

    A common (up to 70% of women) self limiting condition occurring within a few days of delivery. Characterized by mood lability, weeping, depression, fatigue, anxiety, confusion, difficulty concentrating, and depersonalization

    Postpartum depression

    A condition (~ 10%) occurring within days to weeks following delivery and lasting more than 2 weeks. Characterized by  vegetative signs of depression, tearfulness, anxiety, loss of interest in normal activities, guilt, inadequacy in coping with the infant duration, thoughts of suicide. Typically requires treatment for up to 6 months with antidepressants.

    Postpartum psychosis

    Uncommon condition occurring within a few days and up to 4 weeks after delivery. Characterized by auditory hallucinations, delusions, euphoria, grandiosity, hyperactivity, and inappropriate affect. There is a high risk of infanticide and a high chance of developing psychosis in the future.  Treatment usually requires hospitalization.

    Preeclampsia is a disease of pregnancy that affects the lining of the mother's blood vessels causing high blood pressure, leaking of fluid from the blood vessels, and damage to multiple organs. Preeclampsia is believed to be caused by an abnormal placenta releasing higher than normal amounts of substances that control the growth of blood vessels and the placenta

    Pregnancy induced hypertension , PIH

    Obsolete term for gestational hypertension.

    Preimplantation genetic diagnosis, PGD

    Testing for a specific genetic disease , such as cystic fibrosis,  in an embryo prior to transferring the embryo to the uterus .

    Preimplantation genetic screening, PGS

    Testing for chromosome number in an embryo prior to transferring the embryo to the uterus . Techniques such as  comparative genomic hybridization (CGH) test for all 23 pairs of chromosomes.


    Less than 37 completed weeks' (less than 259 days) of gestation

    Pseudotumor cerebri (PTC) also known as idiopathic intracranial hypertension (IIH)

    A condition of unknown cause characterized by increased intracranial pressure, with normal cerebrospinal fluid composition, and no  abnormalities on  neuroimaging.  Increased pressure on the  optic nerves may cause  swelling of the optic discs (papilledema) and loss of vision.  The most common symptom of IIH is headache.


    The first movements of the fetus felt by the woman on average at 19 weeks during the first pregnancy, and as early as 14 weeks during subsequent pregnancies.

    Red blood cell distribution width % (RDW)

    The variability of red blood cell size (anisocytosis). RDW (%) = {SD of red blood cell volume (fL)/MCV (fL)} x 100

    Respiratory distress syndrome (RDS, hyaline membrane disease ,HMD)

    A condition of the lungs where the lungs are too stiff to expand because a substance (surfactant) is not present to prevent the tiny air sacs in the lungs (alveoli) from collapsing and sticking together. Damaged cells collect in the airways and form a glassy (hyaline) membrane over the alveoli. RDS is most likely to occur in premature infants less than 32 weeks' gestational age, and is twice as common in boys.

    Round ligaments

    The round ligaments of the uterus are two flattened bands extending from each side of the uterus that proceed forward through a tunnel in the abdominal wall (the inguinal canal) to the large folds of skin at the opening of the vagina (labium majus).

    Round ligament pain

    Sharp pain in the lower abdomen or groin caused by spasm of the round ligaments of the uterus. The pains usually last a few seconds and are associated with rapid movement or rolling over during sleep.

    Rupture of membranes (ROM, “breaking of the water bag” )

    Breaking or tearing open of the fluid filled amniotic sac . Often described as a "gush of fluid".

    Shoulder dystocia

    An average head-to-body delivery time more than 60 seconds, also  defined as "a delivery that requires additional obstetric maneuvers following failure of gentle downward traction on the fetal head to effect delivery of the shoulders." Shoulder dystocia is usually caused by the anterior shoulder becoming stuck behind the mother's pubic bone.


    A pregnancy with only one fetus in the uterus.

    Small for gestational age (SGA)

    Weight below the 10th percentile for gestational age. Most small for gestational age fetuses are small because of constitutional factors such as female sex or heredity.

    Smith Lemli Opitz Syndrome  (SLOS)

    A condition characterized by  growth retardation, microcephaly, moderate to severe intellectual disability, and malformations inluding cleft palate, cardiac defects, underdeveloped external genitalia in males, postaxial polydactyly, and 2-3 syndactyly of the toes. The symptoms and severity of SLOS varies greatly in affected individuals  and individuals have been described with normal development and only minor malformations. SLOS is caused by mutations in the DHCR7 gene. The DHCR7 gene provides instructions for making an enzyme called 7-dehydrocholesterol reductase which is involved in the production of cholesterol . SLOS is inherited in an autosomal recessive manner.

    Nowaczyk MJM. Smith-Lemli-Opitz Syndrome. 1998 Nov 13 [Updated 2013 Jun 20]. In: Pagon RA, Adam MP, Ardinger HH, et al., editors. GeneReviews® [Internet]. Seattle (WA): University of Washington, Seattle; 1993-2016. Available from: http://www.ncbi.nlm.nih.gov/books/NBK1143/

    Sonogram (Ultrasound)

    An image or images produced by collecting  sound waves reflected from structures inside the body.


    Light vaginal bleeding.


    The level of the presenting part in the birth canal in relation to the ischial spines of the pelvis. The spines represent 0 station. The presenting part is described as being from -1 to -5 cm above the spines or +1 to+ 5 cm below the spines. A station of + 5 cm would correspond to the presenting part at the vaginal opening (introitus).

    Stress test (Contraction stress test,CST, oxytocin contraction stress test)

    A method of testing fetal well-being and in particular the function of the placenta under stress. The study is performed by making a graphical recording of the fetal heart rate using an electronic monitor. The tracing is observed for late decelerations.


    A fetal death that occurs during pregnancy at 20 weeks' or greater gestation.

    Subchorionic hematoma

    A blood clot beneath the placenta.

    Succenturiate placenta

    One or more accessory placental lobes connected  to the main placenta by blood vessels.  There is an increased risk for postpartum hemorrhage and infection  due to retained placenta with a succenturiate placenta. Sometimes the blood vessels that connect the lobes of the placenta  cross over or near the opening of the cervix leaving the blood vessels vulnerable to rupture. This latter condition is called type II vasa previa


    A substance produced in the lungs that prevents the tiny air sacs (alveoli) in the lungs from collapsing and sticking together by reducing surface tension.


    Sutures (stitches) : Sterile, threadlike materials made of catgut, silk, or wire used by surgeons to sew tissues together  OR
    Sutures : The fibrous joints between the skull bones .


    Anything that can cause a birth defect .

    Term pregnancy

    The four definitions of the types of ‘term’ deliveries are:

    Postterm: Between 42 weeks 0 days and beyond

    Tetralogy of Fallot

    A birth defect of the heart consisting of :
    1. Pulmonic stenosis (narrowing of the pulmonary artery).
    2. A ventricular septal defect (VSD). The VSD causes cyanosis (bluish discoloration of the skin due to lack of oxygen) by allowing blood to flow from the right side of the heart to the left side without passing through the lungs.
    3. Malignment of the aorta so that it arises from the VSD or the right ventricle instead of directly from the left ventricle
    4. Right ventricular hypertrophy (thickening of the right heart chamber that pumps blood to the lungs).


    A group of inherited blood disorders characterized by moderate to severe anemia. Thalassemias are caused by defects in the genes that control production of globins, the building blocks of hemoglobin (the oxygen carrying molecule in red blood cells).


    A lower than normal number (count) of platelets in the blood. Platelets are cell fragments in the blood that help to form blood clots.


    The concentration of an antibody in the blood.


    A substance that decreases uterine contractions.


    Old name for preeclampsia


    Toxoplasma gondii is a protozoan parasite that infects most species of warm blooded animals and can cause the disease toxoplasmosis. Most pregnant women who acquire the infection have no symptoms. Some may experience malaise, low grade fever, and lymphadenopathy. Prenatally acquired T gondii may infect the brain and retina of the fetus and can cause chorioretinitis, intracranial calcifications, and hydrocephalus.

    Transverse lie

    The long axis of the fetus is perpendicular to the long axis of the mother. The fetus is laying either on its side, back,  or belly.


    On ultrasound examination the junction of two amniotic sacs forms a 90 degree angle with the placenta. The T-sign strongly indicates that there is a single placenta (monochorionic).

    Twin peak sign, Lambda sign

    On ultrasound examination the presence of a triangular projection of placental tissue extending between two amniotic sacs. The twin peak sign strongly indicates that there are two separate placentas (dichorionic).

    Umbilical arteries

    Blood vessels originating from the fetal internal iliac arteries that carry all the oxygen depleted blood from the fetus through the umbilical cord to the placenta.

    Umbilical cord

    The flexible tube that connects the fetus at the abdomen with the placenta.

    Uterine contractions

    Recurrent tightening and relaxation of the uterus

    Uterine rupture

    A tear through the entire thickness of the uterine wall.

    Uterus (womb)

    The pear-shaped reproductive organ in a woman's pelvis. The lower narrow part of the uterus (the cervix) opens into the vagina.

    Vacuum extraction


    Vaginal birth

    Delivery of an infant through the birth canal (vagina).

    Vaginal birth after cesarean ( VBAC )


    Varicella-Zoster virus (Chickenpox, shingles)




    Vasa previa

    Unsupported fetal blood vessels running over the cervix  that are vulnerable to bleeding. Vasa previa occurs with velamentous cord insertion and succenturate lobes as the frees fetal vessels cross the membranes.

    VATER association


    Velamentous cord insertion

    Insertion of the fetal blood vessels on the membranes at the periphery (edge)  instead of directly in the middle of the  placenta.

    Venous thrombosis

    Formation of a  blood clot  inside of a vein



    Vertex ( vertex presentation )


    Vernix (vernix caseosa)


    Very low birth weight (VLBW)


    Vibroacoustic stimulation (VAS)

    Use of a sound emitting device  placed on the maternal abdomen  to  check on the well-being of the fetus

    VSD ( Ventricular septal defect )


    Walking epidural


    Wharton's jelly

    Womb ( uterus )

    The pear shaped reproductive organ in a woman's pelvis.


    X-Linked recessive trait

    A trait transmitted by a gene located on the x chromosome; also called sex-linked. Read more...

    Yeast Infection

    A vaginal yeast infection (also known as vulvovaginal candidiasis) is an infection of the vagina most commonly caused by the yeast Candida albicans, a type of fungus.  

    Yolk sac

    A membranous structure outside of the embryo that serves as the early site for the formation of blood.


    Zidovudine ,ZDV,  Retrovir,   formerly called azidothymidine [AZT])

    Drug used in the prevention of maternal to fetal HIV-1 Transmission

    Zika virus

    Zika virus is a flavivirus transmitted primarily by Aedes aegypti mosquitoes. Spread of the virus through blood transfusion and sexual contact have been reported. The virus takes its name from the Zika forest in Uganda where the virus was first isolated in 1947. Infection is usually asymptomatic, and, when symptoms are present, typically results in mild and self-limited illness with symptoms including fever, maculopapular rash, arthralgia, and conjunctivitis. Zika virus infection has been associated with
    the development of Guillain-Barré syndrome, and  in the fetus microcephaly.

    1. Dick GW et. al.Zika virus. I. Isolations and serological specificity. Trans R Soc Trop Med Hyg. 1952 Sep;46(5):509-20. PMID: 12995440
    2. Martines RB, Bhatnagar J, Keating MK, et al. Notes from the Field: Evidence of Zika Virus Infection in Brain and Placental Tissues from Two Congenitally Infected Newborns and Two Fetal Losses — Brazil, 2015. MMWR Morb Mortal Wkly Rep 2016;65(Early Release):1–2. DOI: http://dx.doi.org/10.15585/mmwr.mm6506e1er
    3.  Guilherme Calvet G et. al., Detection and sequencing of Zika virus from amniotic fluid of fetuses with microcephaly in Brazil: a case study Lancet
    Zika Virus CDC
    4. Cao-Lormeau VM, et. al., Guillain-Barré Syndrome outbreak associated with Zika virus infection in French Polynesia: a case-control study. Lancet. 2016 Apr 9;387(10027):1531-9. doi: 10.1016/S0140-6736(16)00562-6. PMID:26948433

    Zygote ( fertilized egg )

    The cell that results from fusion of a sperm and egg at fertilization. After three divisions the zygote is called a morula.


    American College of Obstetricians and Gynecologists. Antepartum Fetal Surveillance. Practice Bulletin no. 9. Washington, D.C. ACOG, 1999.


    Gabbe ed: Obstetrics - Normal and Problem Pregnancies, 4th ed New York, NY, Churchill Livingstone; 2002

    Jones, K.L. ed. Smith’s recognizable patterns of human malformation (5th ed.). Philadelphia: W.B. Saunders.1997

    Resnik R, ed., Maternal-Fetal Medicine, 5th ed., pp. 859–899. Philadelphia: Saunders.


    Woodward PJ ed. Diagnostic Imaging Obstetrics, 1st ed., Manitoba: Amirsys, 2005

    Ogueh O, et al., Obstetric implications of low-lying placentas diagnosed in the second trimester.
    Int J Gynaecol Obstet. 2003 Oct;83(1):11-7. PMID: 14511867

  • Reviewed 10/30/2016

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