The Inside Story: Your Baby in Week Thirty-Seven

Your baby may still be growing, but you probably won't gain any more weight in your third trimester.

fetal development SebastianKaulitzki/

Your baby can benefit from some extra days in the uterus, but he's full-term! He is likely to weigh 6 pounds, and he's probably close to 20 inches long. But even your practitioner can't tell how big your baby will be at birth since some of those 30 pounds or so that you've gained come from increased amniotic fluid, breast size, and placental growth.

In fact, your body weight probably won't tip the scale much higher, but your baby will continue adding ounces. During the few weeks (or days) left before you deliver, your baby may add up to 14 grams of fat each day. At the same time, some of your amniotic fluid is starting to be reabsorbed by your tissues, slightly decreasing the fluid around your baby. This may make it feel as though your baby is moving less, but he's actually just as active as before within his increasingly cramped quarters. As your uterus stretches, more light will permeate your baby's space, and he will move his eyes toward it.

Because placental hormones are now stimulating your breasts to produce milk, those same hormones will cause your baby's mammary glands to swell too. They will shrink back down to size after birth.

At this point, about 3 percent of babies are still breech (positioned with their head up and their feet or buttocks closest to the cervix). Your practitioner may do a pelvic exam to assess the baby's presenting parts. Your baby's feet, hips, head, and buttocks are all fairly easy to distinguish by now.

Originally published in You & Your Baby: Pregnancy.

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