The safety of amoxicillin and clavulanic acid use during the first trimester of pregnancy.

Aims: The goal of the current study was to assess the risk for major congenital malformations following first-trimester exposure to amoxicillin, or amoxicillin and clavulanic acid (ACA).

Methods: A population-based retrospective cohort study was conducted, by linking 4 computerized databases: maternal and infant hospitalization records, drug dispensing database of Clalit Health Services in Israel and data concerning pregnancy terminations. Multivariate negative-binomial regression was used to assess the risk for major malformations following first-trimester exposure, adjusted for mother's age, ethnicity (Bedouin vs Jewish), parity, diabetes mellitus, lack of perinatal care, and the year of birth.