Antenatal Steroid Therapy for Fetal Lung Maturation: Is There an Association with Childhood Asthma?

PURPOSE: This study was designed to test the hypothesis that fetal exposure to corticosteroids in the antenatal period is an independent risk factor for the development of asthma in childhood. METHODS: A population-based cohort study was conducted of all pregnant women who resided in Nova Scotia, Canada, and gave birth to a singleton fetus between January 1989 and December 1998 and lived to discharge. After exclusions, 79,395 infants were available for analysis. Using linked health care utilization records, incident asthma cases between 36 to 72 months of age were identified. Generalized Estimating Equations were used to estimate the odds ratio of the association between exposure to corticosteroids and asthma while controlling for confounders. RESULTS: Over the 10 years of the study corticosteroid therapy increased by threefold. Exposure to corticosteroids during pregnancy was associated with a risk of asthma in childhood: adjusted odds ratio of 1.23 (95% confidence interval: 1.06, 1.44). CONCLUSIONS: Antenatal steroid therapy appears to be an independent risk factor for the development of asthma between 36 and 72 months of age. Further research into the smallest possible steroid dose required to achieve the desired post-natal effect is needed to reduce the risk of developing childhood asthma.