Twins Show No Link Between Early Antibiotics and Childhood Weight

The rise in childhood obesity worries many. Some think early antibiotics might disturb gut bacteria and lead to weight gain. A Dutch study looked at twins to test this idea. Researchers used data from 34, 142 pairs of twins aged about five to fifteen years. They compared twins who had taken antibiotics before age two with those who did not. Because twins share genes and many environmental factors, this design helps isolate the effect of antibiotics. About one in four children had used an antibiotic early on. Only a small percentage were overweight or obese, measured by international BMI standards.

The scientists adjusted for many possible confounders: sex, how the baby was born, birth weight, breastfeeding, mother’s body mass index, and parents’ education. They examined both whether a child was obese (yes/no) and the exact BMI score. Results showed no increase in obesity risk for children who had early antibiotics. The odds ratios hovered around one, meaning the chance of being overweight was unchanged. Even when twins were matched closely, the findings stayed the same. These data suggest that taking antibiotics in infancy does not raise the likelihood of being overweight or obese later. The study’s twin design strengthens this conclusion, as it controls for many shared factors.

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