10 Weeks

Though he's barely the size of a kumquat — a little over an inch or so long, crown to bottom — and weighs less than a quarter of an ounce, your baby has now completed the most critical portion of his development. This is the beginning of the so-called fetal period, a time when the tissues and organs in his body rapidly grow and mature.

He's swallowing fluid and kicking up a storm. Vital organs — including his kidneys, intestines, brain, and liver (now making red blood cells in place of the disappearing yolk sac) — are in place and starting to function, though they'll continue to develop throughout your pregnancy.