Regionalization of NICU care: Premature babies fare better if they are born at hospitals that specialize in caring for them and treat many such babies, because such hospitals have the expertise and equipment to handle their complicated needs. Today, women at risk of premature delivery are transferred to hospitals with advanced NICUs, and babies born early are rushed to such units. This centralization of specialized care, which has developed gradually since the 1970s, has been shown to improve mortality.

Artificial surfactant: Babies born even a few weeks prematurely often lack enough surfactant, a soap-like substance that enables lungs to stay inflated. Since an artificial surfactant came into widespread use in the 1990s, babies have needed less oxygen and ventilation, and are less likely to die or develop lung damage.

Antenatal steroids: If a woman is at risk of delivering early, giving her steroids can speed the baby’s lung development. A 1994 consensus statement by the National Institutes of Health found that this practice reduces the risk of death, respiratory distress syndrome and brain bleeds.

Ventilation: Ventilators force open the lungs and deliver oxygen. In years past, ventilators could keep babies alive but often would scar their lungs. Now many different types of ventilation are used, and babies are breathing better with less damage. High-frequency oscillators shake air into a baby’s lungs at a rate of 600 to 900 shakes per minute, avoiding the stretching that pressure can cause. For others, CPAP (continuous positive airway pressure) delivers pressurized air but doesn’t breathe for the baby.