Prenatal corticosteroid prophylaxis for women delivering at late preterm gestation

We studied patterns of prenatal corticosteroid use, respiratory distress syndrome, and associated mortality rates to assess the congruence between knowledge and clinical practice related to such prophylaxis.

We used data on all live births in the United States (for the years 1989-1991, 1995-1997, and 2002-2004) and Nova Scotia, Canada (for the years 1988-2007). Gestational age-specific temporal trends in infant deaths resulting from respiratory distress syndrome were quantified in the United States, and gestational age-specific temporal trends in corticosteroid use and morbidity (respiratory distress syndrome and intraventricular hemorrhage) were quantified in Nova Scotia.

In the United States, infant deaths associated with respiratory distress syndrome decreased by 48% (95% confidence interval: 46%-50%) from 1989-1991 to 1995-1997 and then decreased by another 18% (95% confidence interval: 15%-22%) by 2002-2004. The latter mortality reduction was evident at 28 to 32 weeks but not 33 to 36 weeks of gestation. Corticosteroid use at 28 to 32 weeks was high in Nova Scotia and increased from 30.7% in 1988-1989 to 50.0% in 1996-1997 and to 52.9% in 2006-2007, whereas rates of use at 33 to 36 weeks were much lower (eg, 6.7%, 17.0%, and 15.7% at 34 weeks in the 3 periods). Increased corticosteroid use at 33 and 34 weeks was estimated to reduce respiratory distress syndrome substantially.

Addressing the knowledge-practice gap in corticosteroid use at 33 to 34 weeks should reduce infant morbidity and mortality rates.