How Do Babies Breathe in the Womb?

Breathing in, Breathing Out

Babies in the womb are surrounded by amniotic fluid, a liquid that fills their lungs and keeps them safe and nourished until they are born. One mystery, though, is how babies breathe in the womb. The answer is that they don’t, at least not really. Don’t start picturing a bunch of unborn babies holding their breath, though. The mother breathes for the unborn baby: Oxygen and carbon dioxide pass between them via the umbilical cord, which connects to the placenta. Mother inhales and delivers oxygen to the baby through their shared blood supply, and when she exhales, she removes carbon dioxide from both of their bodies. This exchange between mother and baby is called fetal respiration.

Practice Moving and Breathing

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How Do Babies Breathe in the Womb?

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At around nine weeks of gestation, unborn babies begin to make a breathing movement. This lets them practice breathing motions before they must breathe outside their mothers’ wombs. Babies don’t actually breathe, though, since all they can do is move around the amniotic fluid that is in the placenta and in their lungs. Most women start to feel their babies move at between 16 and 20 weeks of gestation, but doctors can see movement on an ultrasound as early as eight weeks of gestation.

Lung Development

Although babies practice breathing in the womb, their lungs are not equipped to handle outside air until closer to 35 or 36 weeks of gestation. One of the most common issues for babies born prematurely is that their lungs are not yet ready to breathe oxygen. Because steroids can help speed up lung development, they are often administered to women who are at risk of early labor or preterm delivery. Administering steroids before a premature baby is born not only stimulates lung development, but it also decreases the baby’s mortality risk.

Complications

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Premature Baby Lung Development

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It’s not uncommon for babies to have the umbilical cord wrapped around their necks. In many cases, it’s not dangerous, because the cord can still supply oxygen to the baby throughout the birthing process. If the cord is wrapped too tightly, however, it can cut off oxygen to the baby, which can cause serious issues, such as birth defects or brain injuries. Medical providers check for a wrapped cord during birth and unwrap it if possible. Once your baby is born, the oxygen in the environment triggers the baby’s first true breath.

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