Use of antibiotics during pregnancy and the risk of major congenital malformations: a population based cohort study.

AIMS: Few studies have investigated the link between individual antibiotics and major congenital malformations (MCMs) including specific malformations owing to small sample size. We aimed to quantify the association between exposure to gestational antibiotic and the risk of MCMs.

METHODS: Using the Quebec pregnancy cohort (1998-2008), we included a total of 139 938 liveborn singleton alive whose mothers were covered by the "Régie de l'assurance maladie du Québec" drug plan for at least 12 months before and during pregnancy. Antibiotic exposure was assessed in the first trimester and MCMs were identified within the first year of life.

RESULTS: After adjusting for potential confounders, clindamycin exposure was associated with an increased risk of MCMs (aOR 1.34, 95% CI 1.02-1.77, 60 exposed cases), musculoskeletal system malformations (aOR 1.67, 95% CI 1.12-2.48, 29 exposed cases) and ventricular/atrial septal defect (aOR 1.81, 95% CI 1.04-3.16, 13 exposed cases). Doxycycline exposure increased the risk of circulatory system malformation, cardiac malformations and ventricular/atrial septal defect (aOR 2.38, 95% CI 1.21-4.67, 9 exposed cases; aOR 2.46, 95% CI 1.21-4.99, 8 exposed cases; aOR 3.19, 95% CI 1.57-6.48, 8 exposed cases, respectively). Additional associations were seen with quinolone (1 defect), moxifloxacin (1 defect), ofloxacin (1 defect), macrolide (1 defect), erythromycin (1 defect) and phenoxymethylpenicillin (1 defect). No link was observed with amoxicillin, cephalosporins and nitrofurantoin. Similar results were found when penicillins were used as the comparator group.

CONCLUSIONS: Clindamycin, doxycycline, quinolones, macrolides and phenoxymethylpenicillin in utero exposure were linked to organ-specific malformations. Amoxicillin, cephalosporins and nitrofurantoin were not associated with MCMs.