Purpose: Inhaled corticosteroids (ICS) are the first-line controller therapy for asthma. The objective was to assess the impact of different ICS doses during pregnancy on birth weight (BW) using generalized propensity scores (GPS).
Methods: A cohort of 7374 pregnancies from 6197 asthmatic women giving birth in Quebec (Canada) in 1998-2008 was constructed. The average treatment effects (ATE) of ICS daily doses (0, >0-125, >125-250, >250 μg/day) during pregnancy on BW were estimated using multilevel GPS and a conventional multivariable approach. Additional analyses were done to evaluate the robustness of the results.
Results: Using GPS, we found no significant associations between ICS doses and BW (ATE for >0-125 vs 0 μg/day: 27.62 g, 95% confidence interval (CI): -8.68, 64.10; ATE for >125-250 vs 0 μg/day: 17.07 g, 95% CI: -55.85, 92.16; ATE for >250 vs 0 μg/day: -37.83 g, 95% CI: -117.74, 41.53). Similar results were obtained using the multivariable approach.
Conclusions: While, in our primary analyses, no significant differences were found between the BW of babies exposed to the higher ICS doses, as opposed to no use of ICS, our sensitivity analyses, which adjusted for gestational age in the models, suggest the possibility of a small detrimental effect of the higher ICS doses on BW.