First-trimester exposure to amoxycillin/clavulanic acid: A prospective, controlled study

Aims: The number of published studies on the use of amoxycillin/clavulanic acid during pregnancy is small and so is the number of pregnancies investigated in those studies. In this study we wished to investigate prospectively the safety of intrauterine exposure to amoxycillin/clavulanic acid in a relatively large cohort of women. Methods: Women treated (n = 191) with amoxycillin/clavulanic acid during the first trimester of pregnancy were recruited from two teratogen information centres in Israel. Exposed women were matched for age, smoking habits and alcohol consumption with 191 controls exposed to amoxycillin only for similar medical indications. Results: Maternal age, birth weight, gestational age at delivery, rates of live births and abortions were comparable between the two groups. Rates of major malformations in the amoxycillin/clavulanic acid group (3/158, 1.9%) did not differ significantly from controls (5/163, 3%) (P = 0.49, relative risk = 0.62, 95% confidence interval 0.15, 2.55), and were within the expected baseline risk for the general population. Conclusion: These data suggest that exposure to amoxycillin/clavulanic acid during pregnancy is unlikely to be associated with an increased risk of malformations.