Respiratory distress syndrome, a problem often seen in premature babies. The condition makes it hard for the baby 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 substance in the lungs called surfactant. This substance helps the lungs fill with air and keeps the air sacs from deflating. Surfactant is present when the lungs are fully developed. Neonatal RDS can also be due to genetic problems with lung development. Most cases of RDS occur in babies born before 37 weeks. The less the lungs are developed, the higher the chance of RDS after birth. The problem is uncommon in babies born full-term (at 40 weeks).