TY - JOUR T1 - Prenatal antibiotic exposure and childhood asthma: a population-based study JF - European Respiratory Journal JO - Eur Respir J DO - 10.1183/13993003.02070-2017 VL - 52 IS - 1 SP - 1702070 AU - Keely Loewen AU - Barret Monchka AU - Salaheddin M. Mahmud AU - Geert 't Jong AU - Meghan B. Azad Y1 - 2018/07/01 UR - http://erj.ersjournals.com/content/52/1/1702070.abstract N2 - 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. We sought to characterise the association between prenatal antibiotic exposure and childhood asthma.We performed a population-based cohort study using prescription records, hospitalisation records and physician billing claims from 213 661 mother–child dyads born in Manitoba, Canada between 1996 and 2012. Associations were determined using Cox regression, adjusting for maternal asthma, postnatal antibiotics and other potential confounders. Sensitivity analyses evaluated maternal antibiotic use before and after pregnancy.36.8% of children were exposed prenatally to antibiotics and 10.1% developed asthma. Prenatal antibiotic exposure was associated with an increased risk of asthma (adjusted hazard ratio (aHR) 1.23, 95% CI 1.20–1.27). There was an apparent dose response (aHR 1.15, 95% CI 1.11–1.18 for one course; aHR 1.26, 95% CI 1.21–1.32 for two courses; and aHR 1.51, 95% CI 1.44–1.59 for three or more courses). Maternal antibiotic use during 9 months before pregnancy (aHR 1.27, 95% CI 1.24–1.31) and 9 months postpartum (aHR 1.32, 95% CI 1.28–1.36) were similarly associated with asthma.Prenatal antibiotic exposure was associated with a dose-dependent increase in asthma risk. However, similar associations were observed for maternal antibiotic use before and after pregnancy, suggesting the association is either not directly causal, or not specific to pregnancy.Maternal antibiotic use is associated with childhood asthma, but the association is not specific to antibiotic use during pregnancy http://ow.ly/G5j230jAzs5 ER -