Prenatal Exposure to Antibiotics and Risk of Childhood Obesity in a Multi-Center Cohort Study

Abstract

Mounting evidence has linked postnatal antibiotic use with body mass index (BMI) in children, but the influence of prenatal antibiotic use on offspring obesity risk remains unclear. We aimed to assess the association between fetal exposure to antibiotics and obesity at ages 4 and 7 years among 43,332 children using a multi-center prospective cohort of the U.S. Collaborative Perinatal Project (1959-1976). Antibiotic use was ascertained for mothers during pregnancy. Modified Poisson regression models were used to estimate risk ratios (RRs) of obesity (BMI > 95th percentile) and linear mixed models were applied to assess the association with BMI Z-score. Prenatal exposure to antibiotics repeatedly was associated with childhood obesity at age 7 years, and risk of obesity tended to increase with an increasing number of antibiotic exposures (2-3 times: RR = 1.22, 95% confidence interval [CI]: 1.04, 1.44; ≥ 4 times: RR = 1.34, 95% CI: 1.03, 1.73). The magnitude of association was strongest for repeated exposures in second trimester (RR = 1.40, 95% CI = 1.16, 1.71). Prenatal antibiotic use was not associated with obesity or BMI z-score at age 4 years. These findings support an increased risk of mid-childhood obesity with repeated use of antibiotics during pregnancy.