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 might be a little bigger than the top of a pencil eraser.

Week 8: Baby's eyes are visible

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 are visible. The upper lip and nose have formed. The trunk of your baby's body is beginning to straighten.

By the end of this week, your baby might 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 form, and your baby's eyelids and ears continue developing.

By the end of this week, your baby might be about 3/4 inch (20 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.

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. However, 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 might 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 might be about 2 1/2 inches (60 millimeters) long from crown to rump and weigh about 1/2 ounce (14 grams).

Jul. 10, 2014 See more In-depth