Early Exposure to Antibiotics Associated with Later Weight Gain

Children who take antibiotics during the first 6 months of life are significantly more likely to become overweight by age 3 years, according to the results of a study published online on August 21, 2012, in the International Journal of Obesity.

The researchers conducted a birth cohort study of 11,532 children born in the United Kingdom in 1991 and 1992. They looked at whether the participants were exposed to antibiotics before 6 months, between 6 and 14 months, and between 15 and 23 months of age. They also recorded participants’ body mass at 6 weeks, 10 months, 20 months, 38 months, and 7 years of age.

The results showed that antibiotic exposure before 6 months of age was associated with increased body mass (+0.105 standard deviation [SD] units at 10 months and +0.083 SD units at 20 months of age), an increase in weightfor-length z scores at 10 and 20 months of age, body mass index (BMI) z score at 38 months of age (+0.067 SD units), and overweight (odds ratio of 1.22 at 38 months of age). There was, however, no consistent association between exposure to antibiotics later in infancy and increased body mass. In addition, there was no association between exposure to antibiotics during the first 6 months of life and increased body mass at 7 years of age.