The association between prenatal and early-life antibiotic use and obesity at 4-5 years in the Born in Bradford birth cohort

IntroductionThe prevalence of childhood obesity has quadrupled globally over the last 30 years highlighting the urgency for robust research on modifiable risk factors. This study investigates the association between prenatal and early-life (0-24 months) antibiotic use and obesity at 4-5 years within the Born in Bradford (BiB) cohort, and whether this differs by ethnicity or by sex. MethodsBiB is a large, multi-ethnic birth cohort of 13,858 children in Bradford, UK. Data for children and their mothers were obtained from a baseline questionnaire, linked electronic health records (including maternity records and general practitioner (GP) prescriptions), and anthropometric measurements at school. Logistic regression models were employed to estimate the associations between antibiotic exposure in pregnancy and early-life and having obesity at age 4-5 as the outcome, adjusting for several confounders. ResultsIn this population, nearly a tenth of children had obesity, just over a third were exposed to antibiotics in pregnancy, and nearly three quarters were exposed in the first two years of life. The adjusted analysis revealed no clear evidence of an association between prenatal antibiotic use and having obesity at 4-5 years (aOR 1.09; 95% CI 0.94, 1.27; p= 0.248). However, the associations were stronger in males (aOR 1.24; 95% CI 1.02, 1.52; p= 0.037), and for second trimester exposure (aOR 1.17; 0.97, 1.41). There was strong evidence of an association between early-life antibiotic use and having childhood obesity (aOR 1.36; 95% CI 1.15, 1.62; p=0.0001), with stronger associations in females (aOR 1.58; 95% CI 1.23, 2.02; p=0.0002) and with increasing prescriptions (aOR 1.058; 95% CI 1.029, 1.088; ptrend=0.0001). No effect modification by ethnicity was observed. ConclusionThese findings support those found in previous experimental animal and epidemiological studies, highlighting the importance of early-life antibiotic use as a potential modifiable risk factor for the development of obesity.