So that's why many parents call their babies bean...

The embryo is the size of a small bean, about a half an inch long, this week. If you could see inside yourself, you'd find the fetus has an oversized head in proportion to its body. The embryo's facial features are forming with dark spots where the eyes are, openings where the nostrils will be, and pits to mark the ears.

Protruding buds that will become the arms and legs are even more noticeable now. The embryo's hands and feet look like paddles. Other developments include the growth of the pituitary gland and muscle fibers. You can't hear it yet, but the heart (which has divided into the right and left chambers) is now beating between 100 and 130 beats per minute.

Halfway through this week, the embryo makes its first movements. Unfortunately, you'll have to wait until sometime in the second trimester before you get to enjoy feeling your baby's calisthenics. -- BabyCenter.com