PP-39 Prenatal antibiotic exposure and childhood asthma: a population-based study

Abstract

<h3>Importance</h3> Antibiotic use during infancy alters gut microbiota and immune development, and is associated with an increased risk of childhood asthma. The impact of prenatal antibiotic exposure is unclear. <h3>Objective</h3> To determine and characterise the associa-tion of prenatal antibiotic exposure and childhood asth-ma. <h3>Design</h3> Population-based cohort study using admin-istrative healthcare data. Antibiotic use was determined from prescription records. Asthma was defined using hospitalisation records, physician billing claims, and pre-scription records. Associations were determined using Cox regression and expressed as hazard ratios (HR) and 95% confidence intervals (CI). <h3>Setting</h3> General population in Manitoba, Canada. <h3>Participants</h3> 2 13 661 mother-child dyads born from 1996–2012. <h3>Exposure</h3> Maternal antibiotic use. <h3>Outcome</h3> Child asthma, defined as meeting any of the following criteria after 5 years of age: any hospitalisation for asthma; or ≥2 physician diagnoses of asthma, at least 3 months apart and within a 1 year period; or ≥2 prescrip-tions for asthma medications within a 1 year period. <h3>Results</h3> In our study population, 10.1% of children met the case definition for asthma, and 36.8% were prena-tally exposed to antibiotics. Prenatal antibiotic exposure was associated with an increased risk of asthma (crude HR 1.29; 95% CI 1.26–1.33). This association persisted af-ter controlling for maternal asthma, sex, location of resi-dence, gestational age, number of siblings, and postna-tal antibiotic exposure during infancy (adjusted HR 1.23; 1.20–1.27). However, maternal antibiotic use during the 9 months before pregnancy (adjusted HR 1.28, 1.24–1.31) and 9 months postpartum (adjusted HR 1.32, 1.29–1.36) were similarly associated with childhood asthma. <h3>Conclusions and Relevance</h3> Maternal antibiotic use before, during and after pregnancy was associated with a modest, dose-dependent increase in asthma risk among offspring. While our study does not support a pregnan-cy-specific causal relationship between maternal antibi-otic use and childhood asthma, it remains important to prescribe and use antibiotics judiciously.