(HealthDay News) – Infants exposed to antibiotics at <6 months of age are at higher risk of being overweight in childhood.

Leonardo Trasande, MD, MPP, from the New York University School of Medicine in New York City, and colleagues examined the association between antibiotic use in infancy and body mass in childhood in 11,532 children born in the United Kingdom from 1991–1992.

The researchers found that, after adjusting for known social and behavioral obesity risk factors, infants exposed to antibiotics at <6 months of age had a significantly higher risk of increased body mass at 10 months and 20 months, and increased body mass index z-scores at 38 months of age (overweight odds ratio, 1.22 at 38 months). Antibiotic exposure at 6–14 months of age was not associated with body mass; however, those exposed to antibiotics from 15–23 months of age had significantly higher body mass index z-scores at age 7.

“This study reinforces concerns that early-life antibiotic exposure may cause increases in body mass in later life,” Trasande and colleagues conclude. “It also points to the period from birth to 6 months as a window of special vulnerability to exposure.”

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