Neonatal respiratory distress syndrome (RDS) is most commonly a complication seen in premature infants. The condition makes it difficult to breathe.

Neonatal RDS occurs in infants whose lungs have not yet fully developed.

The disease is mainly caused by a lack of a slippery, protective substance called surfactant, which helps the lungs inflate with air and keeps the air sacs from collapsing. This substance normally appears in mature lungs.

It can also be the result of genetic problems with lung development.

The earlier a baby is born, the less developed the lungs are and the higher the chance of neonatal RDS. Most cases are seen in babies born before 28 weeks. It is very uncommon in infants born full-term (at 40 weeks).

In addition to prematurity, the following increase the risk of neonatal RDS:

• A brother or sister who had RDS
• Diabetes in the mother
• Cesarean delivery
• Delivery complications that lead to acidosis in the newborn at birth
• Multiple pregnancy (twins or more)
• Rapid labor

The risk of neontal RDS may be decreased if the pregnant mother has chronic, pregnancy-related high blood pressure or prolonged rupture of membranes, because the stress of these situations cause the infant's lungs to mature sooner.

The symptoms usually appear within minutes of birth, although they may not be seen for several hours. Symptoms may include:

• Bluish color of the skin and mucus membranes (cyanosis)
• Brief stop in breathing (apnea)
• Decreased urine output
• Grunting
• Nasal flaring
• Puffy or swollen arms or legs
• Rapid breathing
• Shallow breathing
• Shortness of breath and grunting sounds while breathing
• Unusual breathing movement -- drawing back of the chest muscles with breathing

A blood gas analysis shows low oxygen and excess acid in the body fluids.

A chest x-ray shows respiratory distress. The lungs have a characteristic "ground glass" appearance, which often develops 6 to 12 hours after birth. Lung function studies may be needed.

Lab tests are done to rule out infection and sepsis as a cause of the respiratory distress.