Prenatal and post-natal exposure to antibiotics and risk of asthma in childhood

Background: Evidence on the association between post-natal exposure to antibiotics and the development of asthma is extensive, but inconsistent and even less is known about prenatal exposure.

Objective: The aim of this study was to examine the associations between prenatal and post-natal exposure to different antibiotics and the risk of childhood asthma in a population- and register-based nested case-control study.

Methods: All children who were born in 1996-2004 in Finland and diagnosed with asthma by 2006 were identified from a national health register. For each case, one matched control was selected. Information on asthma diagnoses, purchased anti-asthmatic drugs and antibiotics as well as putative confounders was obtained from national health registries. The associations were analysed using conditional logistic regression for children diagnosed at the age of 3 years or later (n = 6 690 case-control pairs).

Results: Maternal use of any antibiotics during pregnancy was associated with an increased risk of asthma in the offspring [adjusted odds ratio (OR) = 1.31 (95% confidence interval (CI): 1.21-1.42)]. Several maternal specific antibiotics were associated with the risk of asthma, and the strongest association was observed for cephalosporins [OR = 1.46 (95% CI 1.30-1.64)]. Child's use of antibiotics during the first year of life was associated with an increased risk of asthma [OR = 1.60 (95% CI 1.48-1.73)]. Child's use of cephalosporins [OR = 1.79 (95% CI 1.59-2.01)], sulphonamides and trimethoprim [OR = 1.65 (95% CI 1.34-2.02)], macrolides [OR = 1.61 (95% CI 1.46-1.78)] and amoxicillin [OR = 1.46 (95% CI 1.35-1.58)] was associated with an increased risk of asthma.

Conclusions and clinical relevance: Both prenatal and post-natal exposure to antibiotics was associated with an increased risk of asthma. The potential role of adverse effects of antibiotics on the gut microbiota and the development of asthma should be further explored.