Pneumothorax is the collection of air or gas in the space inside the chest around the lungs, which leads to a lung collapse.

This article discusses pneumothorax in infants.

For information about pneumothorax in older children and adults, see: Pneumothorax

A pneumothorax occurs when the tiny air sacs (alveoli) in a baby’s lung burst, leaking air into the space between the lung and chest wall (pleural space).

The most common cause of pneumothorax is respiratory distress syndrome, which occurs in babies who are born too early (premature).

• Because the baby's lungs lack a slippery substance (surfactant), the tiny air sacs are not able to expand as easily.
• If the baby is put on a breathing machine (mechanical ventilator), there is extra pressure on the baby's lungs, which can sometimes burst the air sacs.

Meconium aspiration syndrome is another cause of pneumothorax in newborns. As the baby is being born, he or she may breathe in the first bowel movement, called meconium. This may cause breathing problems and the need for a breathing machine.

Less commonly, an otherwise healthy baby can develop an air leak when he or she takes the first few breaths after birth. This occurs because of the pressure needed to expand the lungs for the first time.

Pneumothorax is more common in boys than girls.