Prenatal Corticosteroids Cut Risks Associated with Late-Preterm Delivery

By Amy Orciari Herman

Edited by André Sofair, MD, MPH, and William E. Chavey, MD, MS

Giving betamethasone to women at risk for late-preterm delivery could help protect their newborns against respiratory complications, according to a New England Journal of Medicine study.

Researchers enrolled 2800 women with singleton pregnancies at 34 weeks to 36 weeks 5 days of gestation who were likely to deliver before 37 weeks (e.g., those with preterm labor with intact membranes, or spontaneous rupture of membranes). Women were randomized to receive two intramuscular injections of betamethasone (12 mg) or placebo 24 hours apart.

The primary composite outcome — the infant's need for respiratory support within 72 hours after birth, stillbirth, or neonatal mortality — occurred significantly less often with betamethasone than with placebo (11.6% vs. 14.4%). Of note, there were no stillbirths or neonatal deaths. The researchers estimated that 35 women would need to be treated to prevent one instance of the primary outcome. Betamethasone also decreased severe respiratory complications.

Treatment was associated with more neonatal hypoglycemia, but this was generally self-limiting.

Dr. Allison Bryant of NEJM Journal Watch Women's Health said: "This practice-changing work demonstrates what we have suspected for some time: that the beneficial effects of antenatal corticosteroids are not limited to neonates delivered at the earliest gestational ages."