Journal Issue: Low Birth Weight Volume 5 Number 1 Spring 1995
Corticosteroids: Drugs to Accelerate Fetal Lung Maturity
During the late 1960s, while studying the initiation of labor in sheep, it was observed that prematurely delivered lambs exposed prenatally to corticosteroids survived longer than placebo-treated control animals. A subsequent randomized, placebo-controlled trial of a corticosteroid, betamethasone, among pregnant women demonstrated clear reductions in the incidence of respiratory distress syndrome (lungs too immature to allow normal breathing) and neonatal mortality. A reduction in the incidence of respiratory distress syndrome was detected only if corticosteroids were given between one to seven days prior to the delivery.26
Since this landmark study, other randomized trials have confirmed and extended these findings. In addition to the reduction of respiratory distress syndrome, studies have shown an overall reduction in neonatal death, cerebral hemorrhage (bleeding in the brain), and necrotizing enterocolitis (damage to the intestine). There was no strong evidence suggesting adverse effects of corticosteroids.27 Infants who were exposed to corticosteriods before birth have been followed for three to six years and have shown no impairment in physical, cognitive, or psychosocial development.28,29
Despite this overwhelming evidence that steroids are of great benefit in preventing morbidity and mortality in preterm infants, they are not universally used in all situations where they could be of benefit. It is estimated that only 12% to 18% of women who deliver very preterm births are treated with antenatal corticosteroids.30,31 In contrast, tocolytic drugs are widely used, yet their benefit is not nearly so clear. The reason may be that the obstetrician sees the immediate benefit of tocolytic drugs in the cessation of contractions. However, the benefits of steroids are seen after the delivery and are, therefore, not as obvious to obstetricians. One need only look at the tremendous savings in dollars and time spent in the neonatal intensive care unit to see the clear benefits of antenatal steroid use.31
The conclusion of a recent consensus development conference sponsored by the National Institutes of Health is that antenatal steroid therapy is indicated for women at risk of preterm delivery and that its widespread use could result in a substantial decrease in neonatal morbidity and mortality, and could produce substantial cost savings. As a result of these conclusions, it behooves the obstetrician to look beyond the bedside and consider antenatal steroid administration when treating women with preterm labor because failure to do so is costly in terms of the health of the newborn and increased medical care costs.