Prenatal exposure to acid-suppressive drugs and the risk of childhood asthma: a population-based Danish cohort study

Background Proton pump inhibitors (PPIs) may activate the immune system and cause asthma. Methods In this cohort study, 197 060 singletons born between 1996 and 2008 in northern Denmark were followed until the end of 2009. Data were obtained through Danish medical registries. Asthma in offspring was defined as at least two prescriptions of both a fl-agonist and an inhaled glucocorticoid and/or a hospital diagnosis of asthma during the follow-up. Cox proportional-hazard regression was used to compute incidence rate ratios, adjusting for covariates. Res u Its A total of 2238 (1,1%) children were prenatally exposed to PPIs and 24 506 (12,4%) children developed asthma during follow-up (median followup = 6.8 years). The adjusted IRR (aIRR) of asthma associated with prenatal exposure to PPIs was 1.41 (95% confidence interval (CI): 1.27-1.56), compared with those unexposed. The association did not vary by trimester of exposure, and prenatal exposure to H2RAs was associated with similar increase in risk. The aIRR for maternal PPI and H2RA use in the year after, but not during pregnancy was 1,32 (95% CI: 1,20-1.46) and 1,13 (0.93-1.36), respectively, compared with non-use during and in the year after pregnancy.