Respiratory distress syndrome (RDS), also known as infant RDS and once known as hyaline membrane disease, is an acute lung disease present at birth, most frequently affecting premature babies. Abnormal layers of tissue called hyaline membranes keep oxygen breathed into the lungs from passing into the bloodstream. The lungs are said to be "airless." Without treatment, the infant will die within a few days after birth, but if oxygen can be provided, and the infant receives modern treatment in a neonatal intensive care unit, complete recovery with no after-effects can be expected.

If a newborn infant is to breathe properly, the small air sacs (alveoli) at the ends of the breathing tubes must remain open so that oxygen can get into the tiny blood vessels that surround the alveoli. Normally, in the last months of pregnancy, cells in the alveoli produce a substance called...