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How do babies breathe in the womb after the water breaks?

When a woman’s water breaks before labor starts, it is called prelabor rupture of membranes (PROM). This occurs in about 8-10% of term pregnancies. When the amniotic sac ruptures, the amniotic fluid that surrounds and protects the baby during pregnancy leaks out through the vagina. This fluid is what some people refer to as the woman’s “water breaking.”

How do babies get oxygen before birth?

During pregnancy, the baby gets oxygen from the mother’s blood supply through the placenta and umbilical cord. The baby does not use its lungs to breathe until after birth. Inside the womb, the baby’s lungs are filled with amniotic fluid. This fluid helps the lungs grow and develop.

Oxygen passes from the mother’s blood into the baby’s blood through the placenta. The umbilical cord connects the placenta to the baby and transports oxygen-rich blood to the baby. After picking up oxygen, the baby’s blood travels back through the umbilical cord to the placenta. From there, blood flows back to the mother’s blood supply to release carbon dioxide and pick up more oxygen.

Fetal breathing movements

Even though the baby does not use its lungs to breathe inside the womb, it does make breathing-like movements. These movements of the diaphragm look like breathing, but the baby is not actually inhaling amniotic fluid or air.

These fetal breathing movements are crucial for proper lung development. They help strengthen the lungs in preparation for breathing after birth. Fetal breathing movements become more frequent leading up to birth.

How do babies breathe after the water breaks?

After the amniotic sac ruptures, also called the water breaking, the baby continues to get oxygen from the mother through the placenta and umbilical cord. The baby does not usually start breathing through its lungs until after delivery.

However, there are a few ways a baby may try to breathe after the water breaks:

  • Breathing in amniotic fluid: If the baby’s head is down in the pelvis after the water breaks, it may try to inhale some amniotic fluid into its lungs. This is called fetal breathing.
  • Breathing in air: During delivery, especially a vaginal birth, the baby may take some breaths at the perineum. As the head is exposed to air, the baby may attempt to inhale.
  • Crying: Once the baby’s head or body is delivered, it may start crying. Crying requires inhaling air and making sounds.

However, most babies do not make significant breathing efforts until after the entire body is delivered. After birth, the umbilical cord is clamped and cut, and the baby must transition to using its own lungs to breathe air.

Do babies breathe underwater after the water breaks?

No, babies do not breathe underwater after the amniotic sac ruptures. Even though the protective bag of fluid is gone, the baby is still submerged in amniotic fluid inside the uterus. The baby continues to receive oxygen from the mother through the umbilical cord.

Breathing underwater is not necessary or beneficial for the baby. Fetal lungs are filled with amniotic fluid during development. If the baby tries to breathe in the fluid, it may cause complications like pneumonia or difficulty transitioning after birth.

Risks of umbilical cord compression

After the water breaks, the umbilical cord is no longer cushioned by the amniotic fluid. It is possible for the cord to become compressed, especially during contractions or labor. This can temporarily cut off some of the baby’s oxygen supply.

Signs of umbilical cord compression include:

  • Changes in the baby’s heart rate, like decelerations
  • Decreased fetal movement
  • Changes in amniotic fluid color or debris

If umbilical cord compression is suspected after PROM, immediate delivery may be recommended. This reduces the risk of harm to the baby from lack of oxygen.

How do babies transition to breathing after birth?

Babies go through an important transition after delivery to start breathing with their lungs and obtain oxygen independently. This transition involves several steps:

  1. Clamping the umbilical cord stops oxygen transfer from the placenta. This triggers the baby to start breathing.
  2. The first breaths a newborn takes are short and irregular as the lungs inflate.
  3. The baby’s first cries help push fluid out of the airways and inflate the lungs.
  4. As the lungs inflate fully, regular breathing patterns establish within about 10 minutes.
  5. Oxygen saturation increases as blood flow redirects from the umbilical cord to the baby’s lungs.

If a baby has difficulty transitioning and establishing regular breathing, medical interventions may be needed. This includes supplemental oxygen, suctioning fluid from airways, or breathing support like CPAP.

How is fetal oxygenation monitored after PROM?

After the amniotic sac ruptures before labor starts, monitoring the baby is important to ensure it is getting adequate oxygen. Monitoring methods may include:

  • Electronic fetal monitoring: A fetal heart rate monitor placed on the mother’s abdomen tracks the baby’s heart rate patterns for signs of oxygen deprivation.
  • Ultrasound: Doppler ultrasounds periodically assess the baby’s heart rate. Fluid levels, breathing movements, and cord blood flow may also be checked.
  • Fetal pulse oximetry: A sensor on the baby’s head or buttocks provides an oxygen saturation reading.
  • Biophysical profile: Ultrasound assesses the baby’s breathing, movements, muscle tone and amniotic fluid level.

Results from monitoring will guide whether early delivery is recommended for the baby’s safety.

How are babies delivered after PROM?

The method of delivery after PROM depends on several factors:

  • Gestational age
  • Signs of infection
  • Fetal monitoring results
  • Onset of labor
  • Risk factors like placental abruption

In many cases, if labor does not start within 24 hours after membrane rupture, induction of labor may be recommended. Waiting longer after PROM increases the risk of infection to both mother and baby.

Some options for delivery after PROM include:

  • Spontaneous vaginal delivery: Contractions begin naturally and the baby is born vaginally.
  • Induced vaginal delivery: Oxytocin or prostaglandin medications are given to start labor and contractions.
  • Planned cesarean delivery: A c-section is scheduled instead of waiting for labor.

Vaginal birth is usually preferred after PROM if the baby is in a head down position. Cesarean delivery may be recommended for situations like placenta previa, active genital herpes lesions, or fetal distress.

Risk of umbilical cord prolapse

One risk after the water breaks before labor is umbilical cord prolapse. This is when the umbilical cord slips through the open cervix before the baby, ending up in the vagina or outside the uterus.

The cord can become compressed during contractions or delivery. This cuts off the baby’s oxygen supply. Cord prolapse is an obstetric emergency requiring urgent c-section delivery.

How soon should delivery occur after PROM?

Term Pregnancy (37+ weeks) Preterm Pregnancy (<37 weeks)
Delivery within 24 hours after PROM is often recommended for term pregnancies if labor does not start spontaneously. With preterm PROM, waiting and monitoring may be attempted for days to weeks to allow further development.
The risk of serious infection to mother and baby increases after 24 hours. Steroids may be given to help mature the baby’s lungs before delivery.

The timing of delivery after PROM depends on many factors like gestational age, signs of infection, and fetal status. For term pregnancies, delivery within 24 hours is often ideal if labor does not start on its own.

For preterm PROM before 37 weeks, prolonged monitoring may be attempted to allow the baby more time to develop. The risks and benefits must be weighed carefully in these cases.


When a woman’s water breaks before labor starts, it is called prelabor rupture of membranes (PROM). Even after the amniotic sac ruptures, the baby continues to receive oxygen from the mother through the placenta and umbilical cord.

Babies do not usually breathe underwater with their lungs after PROM. Most babies do not take their first breaths until exposed to air during the delivery process.

After PROM, fetal wellbeing needs to be closely monitored for signs of oxygen deprivation. Delivery is often recommended within 24 hours in term pregnancies if labor does not start spontaneously.

Careful monitoring and management after PROM allows the transition to breathing after birth to go smoothly so babies can establish regular respiration and maintain healthy oxygen levels.