Every pregnant woman wonders -- often with a wince or two -- how a seven-, eight-, or even nine-pound baby manages to fit through an opening roughly the diameter of a bagel. But Mother Nature equips infants with a soft skull for a reason. "When you touch a newborn's head, it feels almost like tiles," says Richard Auerbach, MD, neonatologist at the Joe DiMaggio Children's Hospital, in Hollywood, Florida. "And where the grout would be are soft areas that allow a baby's head to remain pliable as it passes through the birth canal." The head of every baby born vaginally becomes misshapen to some degree during the birth process, but even the most pronounced "conehead" returns to normal within a few days.
Labor produces mechanical and physiological changes that help prepare your baby for her first gulp of air. "A fetus doesn't get his oxygen from the air, so he has to get it from his mom," explains Sandy Falk, MD, clinical instructor of ob-gyn at Brigham and Women's Hospital, in Boston. "In utero, oxygen is delivered through the placenta to the baby." But when the baby is born and the umbilical cord is clamped shut, the placenta can no longer do its job, so the lungs take over. In the womb, a fetus's lungs are filled with a fluid that helps them mature. "Labor dries up this fluid so the lungs can expand and fill with air after birth," notes Dr. Auerbach.
Your baby's lungs will also begin pumping more blood through them after she's born. In the womb, the blood bypasses these organs due to pressure. During birth, the pressure in the baby's lungs drops and blood starts flowing through them normally.
How does a baby who's coming from a 98.6-degree environment adjust to a 70-degree delivery room? The thyroid plays a big role. "At birth, a baby's thyroid level is sky-high," says Dr. Auerbach. That surge is caused both by exposure to cold and by increased adrenaline. Elevated thyroid levels cause heat production from a type of fat called "brown" fat, which is essential in helping a newborn regulate its temperature outside the womb.
Doctors now know that newly born babies probably feel pain. But exactly how much they feel during labor and delivery is still debatable. "If you performed a medical procedure on a baby shortly after birth, she would certainly feel pain," says Christopher E. Colby, MD, director of the neonatology fellowship program at Mayo Clinic in Rochester, Minnesota. "So it may be that a baby does feel pain while she's going through the birth canal -- but no one knows for sure." If pain does register with a baby, some experts liken it to a feeling of being gradually squeezed. "It's hard to say what a baby senses," says Dr. Auerbach. "But your pain and the baby's pain are totally different. It's possible that the baby's pain may be what it feels like to squeeze through a tight space -- such as the feeling of compression you get when you try to crawl under a fence."
Just as there's no way to tell what kind of pain a baby feels when he travels through the birth canal, doctors are also unsure about how much a baby sees or hears during labor. But it is well established that a baby has some auditory abilities before he enters the world. In fact, doctors say that hearing a mother talk and sing during nine months in the womb allows a baby to recognize the sound of her voice after he's born -- an integral part of parent-child bonding. A baby's eyesight before birth, by contrast, is harder to gauge. But after he's born, we know his vision is blurry at first and he can't focus well. When held about 8 to 15 inches away from Mom's face (it's no coincidence that this is around breast level, where he usually feeds), he does have the ability to detect his mother's facial features -- another important element of bonding.
As your labor progresses, your infant will be doing the best he can to push the process along.
How is the birth experience of a c-section baby different from the experience of a vaginally born baby? For one thing, a baby who hasn't squeezed through the birth canal is likely to be born with a rounder, less pinched-looking head.
Another key difference: A c-section baby's breathing may be faster and shallower than that of a baby who has been born after labor. That's because the contractions of his mother's womb during labor -- as well as the compression of his own chest in the birth canal -- both help expel fluid from the lungs. Consequently, a c-section baby can be born with what's known as transient tachypnea of the newborn, or "wet lung," and may have to breathe faster and harder until the fluid is absorbed. The good news: The issue usually resolves itself in 24 to 48 hours.
Copyright © 2008. Used with permission from the January 2008 issue of Parents magazine.All content on this Web site, including medical opinion and any other health-related information, is for informational purposes only and should not be considered to be a specific diagnosis or treatment plan for any individual situation. Use of this site and the information contained herein does not create a doctor-patient relationship. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your own health or the health of others.