Childhood Pulmonary Outcomes After Late Preterm Antenatal Corticosteroids

OBJECTIVE: To evaluate whether antenatal betamethasone affects childhood respiratory impairment. METHODS: This was a prospective follow-up study of children aged 6 years and older from parents in the ALPS (Antenatal Late Preterm Steroids) trial randomized to betamethasone or placebo from 34 0/7 to 36 6/7 weeks of gestation. Primary outcome composite included the following: 1) abnormal spirometry, forced expiratory volume in 1 second (FEV 1 ) below the lower limit of normal, FEV 1 /forced vital capacity (FVC) below the lower limit of normal, or FVC below the lower limit of normal, defined as below the 5th percentile by the Global Lung Initiative; 2) physician-diagnosed asthma and daily asthma medication; or 3) daily asthma medication use in the past year. Children whose parents were enrolled in a concurrent trial were recruited to provide a term reference cohort for lung function. Adjusted analyses were performed controlling for confounders. RESULTS: Of 2,831 ALPS children, 1,218 enrolled, and 1,194 (98.0%) completed spirometry. There were no differences in the primary outcome (35.3% betamethasone, 35.8% placebo; adjusted relative risk [RR] 1.02, 95% CI, 0.87-1.18) or its individual components, although ever-noting wheezing or whistling in the chest was less common (40.7% betamethasone, 45.5% placebo, adjusted RR 0.88, 95% CI, 0.77-0.996). Compared with 432 children from the term reference cohort, ALPS children had more wheezing with exercise in the past year (7.2% betamethasone vs 4.4% term control group, adjusted RR 1.77, 95% CI, 1.03-3.06; 8.8% placebo vs term control group, adjusted RR 2.09, 95% CI, 1.25-3.48). CONCLUSION: Among children aged 6 years or older, late preterm antenatal exposure to betamethasone was associated with lower rates of wheezing or whistling in the chest but no differences in other respiratory outcomes.