Healthy pregnancy (16)
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- Fetal development: The first trimester
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- Fetal development: The second trimester
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Fetal development: The first trimester
Week 7: Baby's head develops
Seven weeks into your pregnancy, or five weeks after conception, your baby's brain and face are rapidly developing. Tiny nostrils become visible, and the eye lenses begin to form. The arm buds that sprouted last week now take on the shape of paddles.
By the end of this week your baby may be 1/4 to 1/3 inch (7 to 9 millimeters) long — a little bigger than the top of a pencil eraser.
Week 8: Movement begins
Eight weeks into your pregnancy, or six weeks after conception, your baby's arms and legs are growing longer, and fingers have begun to form. The shell-shaped parts of your baby's ears also are forming, and your baby's eyes and nipples are visible. The upper lip and nose have formed. The trunk of your baby's body is beginning to straighten.
Your baby may begin to move this week, but you won't be able to feel it yet.
By the end of this week, your baby may be about 1/2 inch (11 to 14 millimeters) long.
Week 9: Baby's toes form
In the ninth week of pregnancy, or seven weeks after conception, your baby's arms grow, develop bones and bend at the elbows. Toes begin to form, and your baby's eyelids and ears continue developing.
By the end of this week, your baby may be close to 3/4 inch (18 to 22 millimeters) long.
Week 10: Baby's neck begins to develop
By the 10th week of pregnancy, or eight weeks after conception, your baby's head has become more round. The neck begins to develop, and your baby's eyelids begin to close to protect his or her developing eyes.
Although the genitals are developing, it's still too soon to identify your baby's sex.
Week 11: Baby's genitals develop
At the beginning of the 11th week of pregnancy, or the ninth week after conception, your baby's head still makes up about half of its length. But your baby's body is about to catch up, growing rapidly in the coming weeks.
Your baby is now officially described as a fetus. This week your baby's eyes are widely separated, the eyelids fused and the ears low set. Red blood cells are beginning to form in your baby's liver. By the end of this week, your baby's external genitalia will start developing into a penis or clitoris and labia majora.
By now your baby may measure about 2 inches (50 millimeters) long from crown to rump and weigh almost 1/3 ounce (8 grams).
Week 12: Baby's fingernails develop
Twelve weeks into your pregnancy, or 10 weeks after conception, your baby is developing fingernails. Your baby's face now has a human profile.
By now your baby may be nearly 2 1/2 inches (61 millimeters) long from crown to rump and weigh about 1/2 ounce (14 grams).
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- How your baby grows during pregnancy. The American College of Obstetricians and Gynecologists. http://www.acog.org/publications/patient_education/bp156.cfm. Accessed March 20, 2009.
- Knuppel A. Maternal-placental-fetal unit; Fetal & early neonatal physiology. In: DeCherney AH, et al. Current Diagnosis & Treatment Obstetrics & Gynecology. 10th ed. New York, N.Y.: The McGraw-Hill Companies; 2007:1.
- Cunningham FG, et al. Williams Obstetrics. 22nd ed. New York, N.Y.: The McGraw-Hill Companies; 2005:1.
- DeUgarte CM, et al. Embryology of the urogenital system and congenital anomalies of the female genital tract. In: DeCherney AH, et al. Current Diagnosis & Treatment Obstetrics & Gynecology. 10th ed. U.S.: The McGraw-Hill Companies; 2007:1.
- Having twins. The American College of Obstetricians and Gynecologists. http://www.acog.org/publications/patient_education/bp092.cfm. Accessed April 28, 2009.
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