Oxygen is needed in every cell of our body. It first enters the body through the lungs. The oxygen is then picked up by the blood flowing by the lungs. The blood brings oxygen to the rest of the body. In newborns with persistent pulmonary hypertension (PPHN), the blood does not flow by the lungs.

The baby's lungs are not used during pregnancy. Instead, oxygen passes from the mother to the baby through the umbilical cord. This means most of the baby's blood does not need to pass by the lungs. Once the baby is born, the baby's lungs should take over. The blood flow should switch so that it will pass by the lungs. In babies with PPHN, this switch doesn't happen. The blood does not flow go to the lungs as it should. This means that oxygen can not move from the lungs to the rest of the body.

PPHN can be a very serious condition. It can cause both immediate and long-term health problems. It affects about one in every 500-1500 births.

Circulatory System of Infant
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PPHN can be caused by a variety of factors, including:

  • An event or illness during pregnancy or childbirth
    • Meconium aspiration syndrome (the baby inhales meconium—the first stool—prior to or shortly after birth)
    • Severe pneumonia
    • Infection
    • Low blood sugar
    • Birth asphyxia (loss of oxygen to the fetus during delivery)
    • Respiratory distress syndrome —caused by lungs that have not fully developed
    • Use of nonsteroidal anti-inflammatory medications (such as aspirin, ibuprofen, naproxen) by mother during pregnancy
    • Late trimester maternal use of antidepressants (particularly a group called SSRI antidepressants)
    • Amniotic fluid leak
    • Low amniotic fluid (oligohydramnios)
    • Abnormal lung development as a result of congenital diaphragmatic hernia or Potter syndrome
  • Stress during pregnancy
  • Isolated condition with an unknown cause