The study found that on average, children exposed to antibiotics from birth to 5 months of age weighed more for their height than children who were not exposed. Between the ages of 10 to 20 months, this translated into small increases in body mass percentile, based on models that incorporated the potential impacts of diet, physical activity, and parental obesity.
By 38 months of age, exposed children 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, led by Doctor Leonardo Trasande and Doctor Jan Blustein caution that the study does not prove that antibiotics in early life causes young children to be overweight. It only shows that a correlation exists. Further studies will need to be conducted to explore the issue of a direct causal link.
"We typically consider obesity an epidemic grounded in unhealthy diet and exercise, yet increasingly studies suggest it's more complicated," said Trasande. "Microbes in our intestines may play critical roles in how we absorb calories, and exposure to antibiotics, especially early in life, may kill off healthy bacteria that influence how we absorb nutrients into our bodies, and would otherwise keep us lean."
In recent years there has been a growing concern about the overuse of antibiotics, especially in children. Preliminary studies of the microbiome, the trillions of microbial cells inhabiting our bodies and outnumber our own cells 10 to 1, implicate obesity, inflammatory bowel disease, asthma, and other conditions with changes in the microbiome. It is still a field in its infancy, however, and no one has yet proved that altering the composition of bacteria in the body leads to disease.
This is the first time that a study has analyzed the association between the use of antibiotics and body mass starting in infancy. One previous study had identified a link between antibiotic use in early infancy and obesity at seven years of age, but was unable to examine potential impacts of antibiotic use later in infancy on body weight in childhood.
The researchers evaluated the use of antibiotics among 11,532 children born in Avon, United Kingdom, during 1991 and 1992. The children are part of the Avon Longitudinal Study of Parents and Children (ALSPAC), a long-term study that provides detailed data on the health and development of these children.
Antibiotic use only appeared to have an effect in very young infants (those given antibiotics from birth to 5 months of age). Although children exposed to antibiotics at 15 to 23 months had somewhat greater BMI (Body Mass Indices) for their age and gender by the age of 7, there was no significant increase in their being overweight or obese.
MEDICA.de; Source: New York University (NYU) School of Medicine