Your baby has definite alert and resting periods now. She's still much skinnier than she'll be at birth, but she continues to fill out. By the end of this week she'll probably weigh about 1 1/2 pounds.
Her eyes are open now, perhaps even blinking and closing when she sleeps. The nerves around her mouth are becoming sensitive as she prepares to be able to suckle and nourish her own body after birth.
For now, though, you're still nourishing your unborn child via the umbilical cord; your blood carries nutrients to your baby through the cord, which consists of a single vein and two arteries. The umbilical cord is protected against your baby's gymnastics by Wharton's jelly -- a gelatinous goo that keeps the umbilical cord from twisting and knotting as your baby continues to test her muscles and find things to occupy her waking time.
As your baby grows, so does her brain. Deeper grooves and furrows are developing in her cerebral cortex, which is going to be Command Central for many important functions including her ability to see, hear, smell, speak, and walk. Already her brain controls her rhythmic breathing, digestion, and body temperature; these three activities are essential in order for your baby to be able to live outside your body.
Originally published in You & Your Baby: Pregnancy.
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