A nationwide, population-based cohort study published in JAMA Network Open evaluated inhaled corticosteroid continuation during the first trimester and maternal and neonatal outcomes. Among 3,909,084 pregnancies, 6,105 involved prepregnancy inhaled corticosteroid use. Of these, 2,108 women (34.5%) continued inhaled corticosteroids during the first trimester and 3,997 (65.5%) discontinued.

Risks per 1,000 pregnancies for continuation versus discontinuation were 145.6 versus 131.9 for gestational diabetes (weighted risk ratio, 1.05; 95% CI, 0.90-1.22), 131.4 versus 128.6 for preterm birth (0.95; 0.82-1.11), 77.5 versus 58.3 for low birth weight (1.11; 0.89-1.39), and 57.6 versus 42.2 for congenital malformations (1.22; 0.94-1.56). Continuation was not associated with increased risks of these or other maternal and neonatal outcomes. These findings suggest that continued inhaled…