Abstract
Background: Recent studies have reported increased childhood asthma risks after prenatal exposure to antibiotics. Associations could have been influenced by unmeasured confounders.
Objectives: To assess the association between antibiotic use during pregnancy and the development of toddler asthma with a confounding minimizing crossover design. Second, we assessed the influence of time-invariant confounding by comparing results with a case-control design.
Methods: Data was obducted from the prescription database IADB.nl. We conducted a crossover study in which 1,228 children with asthma were compared to their own siblings without asthma, and a traditional matched case-control study. Maternal exposure was defined as ≥1 day of supply of systemic antibiotics during pregnancy. Toddler asthma was defined as having received ≥3 prescriptions for asthma medication within a year before the fifth birthday. Conditional logistic regression was used to estimate crude and adjusted odds ratios(aOR).
Results: The crossover analysis only showed an increase in the toddler's asthma risk if antibiotics were used in the third trimester of pregnancy (aOR 1.37(95%CI 1.02-1.83)). Results were similar in the case-control study after exposure in the third trimester (aOR 1.40(95%CI 1.15-1.47)). In addition, use of antibiotics, independent of trimester of pregnancy, was associated with an aOR of 1.46 (95%CI 1.33-1.58) in the case-control study.
Conclusions: Prenatal exposure to antibiotics in the third trimester of pregnancy is associated with a small increased risk of toddler asthma. This association did not appear to be influenced by time-invariant confounders such as genetic predisposition.
- © 2014 ERS