The Inside Story: Your Baby in Week Sixteen

As you end your 4th month, get ready for an exciting development: You may start feeling your baby move for the first time this week. There's a real person in there, and he's about to make himself known! Your baby is still small enough to fit in the palm of your hand, but barely. He's growing fast now, reaching more than 4 inches in length and weighing in at about 5 ounces. His transparent skin is tinged pink as it adds layers, and he can kick his tiny feet and make grasping motions with his hands. His eyes are becoming increasingly sensitive to light.

By now, all of your baby's muscles and bones are in place, and his nervous system is starting to exert control. Your baby is attached to the placenta by his lifeline, the umbilical cord, and that's growing thicker and stronger as his needs increase. Blood is constantly pulsing through the cord, bringing nutrients to your baby and helping to remove toxins from the amniotic fluid, which fills his trachea each time he opens his mouth. The placenta has grown too, in order to accommodate the thousands of blood vessels that are working hard to exchange nutrients and oxygen between your body and your baby's.

Originally published in You & Your Baby: Pregnancy.

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