Antibiotic Use in Pregnancy, Abnormal Fetal Growth, and Development of Gestational Diabetes Mellitus.

OBJECTIVE:  Antibiotics are commonly used in pregnancy. Prior studies have indicated that antibiotic use in pregnancy may affect birth weight, whereas data in nonpregnant individuals suggest that antibiotic exposure may increase diabetes risk. We evaluated the impact of antibiotic prescriptions during pregnancy on the prevalence of small for gestational age (SGA) and large for gestational age (LGA) birth weight and gestational diabetes mellitus (GDM).

STUDY DESIGN:  This retrospective cohort study of 12,551 women who delivered at a large academic medical center between 2012 and 2014 assessed the number and type of antibiotic prescriptions prior to GDM testing using the electronic medical record. SGA and LGA birth weight and GDM rates were compared among women who were or were not prescribed antibiotics.

RESULTS:  Overall, 3,991 (31.8%) of 12,551 patients received at least one antibiotic prescription. After covariate adjustment, no differences existed in risk of SGA (adjusted odds ratio [aOR]: 1; 95% confidence interval [CI]: 0.88-1.15; p  = 0.94), LGA (aOR: 1; 95% CI: 0.86-1.17; p  = 0.97), or GDM (aOR: 0.90; 95% CI: 0.72-1.13; p  = 0.36) between women who were or were not prescribed antibiotics.

CONCLUSION:  Antibiotic use does not affect the risk of SGA or LGA birth weight or GDM in pregnant women. These results provide reassurance regarding the use of antibiotics when clinically indicated in pregnancy.