Study leader Dr. Leonardo Trasande and Dr. Jan Blustein of the New York University School of Medicine and the NYU Wagner School of Public Service evaluated the use of antibiotics among 11,532 children born in Avon, England, in 1991 and 1992. The children were part of the Avon Longitudinal Study of Parents and Children, a long-term study that provides detailed data on the health and development of these children.
The study, published in the International Journal of Obesity, found on average, children exposed to antibiotics from birth to 5 months weighed more for their height than children who weren't exposed.
By 38 months of age, children exposed to antibiotics had a 22 percent greater likelihood of being overweight. However, the timing of exposure mattered: Children exposed from 6 months to 14 months did not have significantly higher body mass than children who did not receive antibiotics in that same time period.
The researchers cautioned the study did not prove antibiotics in early life cause young children to be overweight; it only showed a correlation. Further studies will need to be conducted to explore the issue of a direct causal link, Trasande said.