Prenatal Testing

Routine medical tests to ensure the health of the mother and unborn child are an important part of a healthy pregnancy. Some tests, including blood pressure and hemoglobin, are given periodically throughout pregnancy while others are given at specific times. These tests may be administered at the obstetrician's office, at a lab or at Greenwich Hospital. Tests may include:

First Trimester

Pap Test

A Pap test to screen for precancerous abnormalities as well as sexually transmitted infections such as HPV, chlamydia and gonorrhea.

Anemia Blood Test

A blood test to check for anemia (low red blood cell count), which can cause fatigue.

Blood Screen

A blood screening to check for blood type, HIV, and hepatitis C, immunity to hepatitis B, immunity to rubella (German measles) and syphilis.

Lab Test

Lab tests to screen for cystic fibrosis, sickle cell, and conditions that are more common among Jewish populations.


An ultrasound to determine the baby's due date.

Urine Test

A urine test to measure sugar and protein levels. Increased sugar in urine may indicate the mother has diabetes. Protein in urine may be a sign of preeclampsia (a condition characterized by pregnancy-induced high blood pressure, protein in the urine, and swelling due to fluid retention).

Chromosomal Abnormality Screening

A first trimester screen for specific chromosomal abnormalities including Down syndrome and Trisomy-18. This noninvasive evaluation combines a maternal blood screening test with an ultrasound evaluation of the fetus to identify risk. The ultrasound (nuchal translucency) portion of this test can also assist in identifying other conditions including cardiac disorders. The results of the nuchal translucency test are evaluated by the maternal-fetal specialists.

Second Trimester Testing

Quad Screen

A series of blood tests (quad screen) that provide information about a woman's risk of having a baby with certain genetic or birth defects. The tests screen for conditions such as open neural tube defects (ONTD), Down syndrome or other chromosomal abnormalities.

The screening is usually performed by taking a sample of the mother's blood between the 15th and 20th weeks of pregnancy. (Some women may have already had a portion of this screening done during their first trimester screen for chromosomal abnormalities.) These tests measure levels of four substances in a pregnant woman's blood:

  • Alpha-fetoprotein screening (AFP) - A protein normally produced by the fetal liver and present in the fluid surrounding the fetus (amniotic fluid)
  • hCG - The human chorionic gonadotropin hormone (a hormone produced by the placenta)
  • Estriol - A hormone produced by the placenta
  • Inhibin - A hormone produced by the placenta

Abnormal levels of AFP and other markers may indicate the need for additional testing. An ultrasound may be performed to confirm the stage of pregnancy and look at the baby's spine and other body parts. Amniocentesis or CVS may be necessary for a more accurate diagnosis.

Second Trimester Ultrasound

In the fifth month (around 20 weeks gestation), a detailed ultrasound is performed to determine if the baby is developing normally and whether the placenta is healthy.

Third Trimester Testing

GBS Test

A test for group B streptococcus (GBS). GBS is a common bacteria that, while usually harmless in adults, can make a baby very ill. A mother who tests positive for GBS is given intravenous antibiotics during labor to protect her baby from the bacteria.

Gestational Diabetes Test

The screening test for gestational diabetes, usually performed at the beginning of the third trimester (around 28 weeks). This test involves a glucose drink followed by measurement of blood sugar levels after one hour. If an abnormally high blood sugar level is present, a three-hour glucose tolerance test may be performed after a few days of following a special diet. If the second test is in the abnormal range, a diagnosis of gestational diabetes is confirmed.

Additional Tests for Women 35 and Older

Women who are of advanced maternal age (35 years and older) may have additional tests such as chorionic villi sampling (CVS) and amniocentesis. These tests are administered by maternal-fetal specialists and are considered routine for older mothers. 

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