In these final weeks before your baby's birth, several subtle changes are taking place that will prepare your baby for delivery.
The lanugo, or soft, thin hairs that cover your unborn baby's body, are starting to fall off. You might still notice some of these downy hairs on your baby's shoulders and back after birth, which is normal. In the lanugo's place, the vernix caseosa — a thick, cheeselike coating — is building up all over the baby's body. This coating helps insulate her body and maintain her temperature in utero. It also helps protect your baby's delicate skin from the acidic amniotic fluid all around her. With delivery fast approaching, the vernix has another function: the thick covering helps your baby glide through the birth canal more easily.
Your baby's digestive system is also preparing for the eventual separation from you, and the umbilical cord. For weeks your baby has been swallowing amniotic fluid and then expelling it through urine. Your baby's digestive system absorbs some nutrients from the fluid but relies on the umbilical cord for most nutrients and sustenance. As the contents from the amniotic fluid work through the small intestine, the leftover waste goes into the bowel. The unborn baby's body forms her first stool, called meconium, in the large intestine, which usually isn't passed until after birth. Some babies push out meconium before birth. If your baby does have a bowel movement before or during delivery, your health care provider will monitor her responses carefully to ensure that she doesn't develop any complications as a result.
Even without an ultrasound, your provider should be able to tell by now how your baby is "presenting" — whether he is positioned upside down, which means his head is ready to come out first, or if he is breech, which means he'll come out bottom-first and needs to be repositioned or birthed via C-section. Your baby's skull, once so soft and pliable, is hardening as calcium is deposited there. His brain still isn't completely closed over with bone, though. His head has fontanels, which are "soft spots" where the skull bones don't completely join together. The largest one is diamond-shape and slightly toward the front of his head. This is the anterior fontanel, and it's the "soft spot" everyone talks about. There is one other noticeable but smaller fontanel toward the back of your baby's head.
Meconium Aspiration Syndrome (MAS): This condition describes when a baby ingests some meconium while in utero or during the birth process. Meconium is a baby's first bowel movement, which is normally passed in the days after delivery. Babies who ingest some of the meconium either through their mouths or into their lungs in utero might be at risk of developing MAS, which can pose a health risk to your baby but often does not lead to any serious problems.
Copyright © 2010 Meredith Corporation.
Images courtesy of the American Institute of Ultrasound in Medicine (AIUM.org).