Your baby begins a period of dramatic change known as the embryonic stage. This stage runs from the 5th through the 10th week of the first trimester of pregnancy. During this stage, the baby is called an embryo. Your baby’s penis or vagina is visible at the end of the embryonic period, but it's not yet possible to tell on an ultrasound if your baby is a girl or a boy. 2 Muscles and movement.
1 Week 5 is the start of the embryonic period.. 2  This is when all the baby's major systems and structures develop. 3  The embryo's cells multiply and start to take on specific functions. 4  This is called differentiation. Gestation is the period of time between conception and birth when a baby grows and develops inside the mother's womb. Because it's impossible to know exactly when conception occurs, gestational age is measured from the first day of the mother's last menstrual cycle to the current date. It is measured in weeks. Most organs form begin to form about 3 weeks after fertilization, which equals 5 weeks of pregnancy (because doctors date pregnancy from the first day of the woman's last menstrual period, which is typically 2 weeks before fertilization). At this time, the embryo elongates, first suggesting a human shape. At the end of the 8th week after fertilization (10 weeks of pregnancy), the embryo is considered a fetus. During this stage, the structures that have already formed grow and develop. The following are markers during pregnancy: By 12 weeks of pregnancy: The fetus fills the entire uterus. Week 5. 1  Week 5 is the start of the embryonic period.. 2  This is when all the baby's major systems and structures develop. 3  The embryo's cells multiply and start to take on specific functions. 4  This is called differentiation. 5  Blood cells, kidney cells, and nerve cells all develop. Gestation is the period of time between conception and birth when a baby grows and develops inside the mother's womb. Because it's impossible to know exactly when conception occurs, gestational age is measured from the first day of the mother's last menstrual cycle to the current date. It is measured in weeks. The fifth week of pregnancy is the time of the first missed period, when most women are only just beginning to think they may be pregnant. Yet already the baby’s nervous system is developing, and the foundations for its major organs are in place. At this stage the embryo is around 2mm long.  embryo period From fertilization to the eigth week of pregnancy, the 23 Carnegie stages of human development pinpoint changes in this extraordinary period-ending when all internal and external structures necessary for fetal growth are present.  Weeks 9 thru 13 – Gestational Age (Fetal Development – Weeks 7 thru 11). At 10 weeks, the embryo is at the end of the embryonic period and begins the fetal period. The fetus has grown to about 3 inches in length and weighs about an ounce. The genitalia have clearly formed into male or female, but still can not be seen clearly on an ultrasound. Week 1 & 2 – Gestational Age. Your menstrual period has just ended, and your body is getting ready for ovulation. For most women, ovulation takes place about 11 – 21 days from the first day of the last period. Fetal development three weeks after conception. The fifth week of pregnancy, or the third week after conception, marks the beginning of the embryonic period. This is when the baby's brain, spinal cord, heart and other organs begin to form. The embryo is now made of three layers. After conception, your baby begins a period of dramatic change known as the embryonic stage. This stage runs from the 5th through the 10th week of the first trimester of pregnancy. During this stage, the baby is called an embryo. 1 Your baby’s penis or vagina is visible at the end of the embryonic period, but it's not yet possible to tell on an ultrasound if your baby is a girl or a boy. 2  Muscles and movement. 3  Muscles develop and the embryo begins to move. Within three weeks, the blastocyte cells ultimately form a little ball, or an embryo, and the baby's first nerve cells have already formed. Your developing baby is called an embryo from the moment of conception to the eighth week of pregnancy. By the end of the second month, your baby is about 1 inch long and weighs about 1/30 of an ounce. At about 6 weeks, your baby's heart beat can usually be detected. After the 8th week, your baby is called a fetus instead of an embryo. Month 3. Your baby's arms, hands, fingers, feet, and toes are fully formed.
http://umm.edu/health/medical/ency/articles/fetal-development http://www.merckmanuals.com/home/women-s-health-issues/normal-pregnancy/stages-of-development-of-the-fetus http://umm.edu/health/medical/ency/articles/fetal-development http://www.nhs.uk/Conditions/pregnancy-and-baby/pages/pregnancy-weeks-4-5-6-7-8.aspx http://www.visembryo.com/baby/pregnancytimeline4.html http://americanpregnancy.org/while-pregnant/first-trimester/ http://www.mayoclinic.org/healthy-lifestyle/pregnancy-week-by-week/in-depth/prenatal-care/art-20045302 http://familydoctor.org/familydoctor/en/pregnancy-newborns/fetal-health/your-babys-development-the-first-trimester.html http://my.clevelandclinic.org/health/diseases_conditions/hic_Am_I_Pregnant/hic-fetal-development-stages-of-growth
period when a baby is an embryo