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.

If you could take a peek inside your womb, you'd spot minute details, like tiny nails forming on fingers and toes (no more webbing) and peach-fuzz hair beginning to grow on tender skin.

In other developments: Your baby's limbs can bend now. His hands are flexed at the wrist and meet over his heart, and his feet may be long enough to meet in front of his body. The outline of his spine is clearly visible through translucent skin, and spinal nerves are beginning to stretch out from his spinal cord. Your baby's forehead temporarily bulges with his developing brain and sits very high on his head, which measures half the length of his body. From crown to rump, he's about 1 1/4 inches long. In the coming weeks, your baby will again double in size — to nearly 3 inches.