Giving babies antibiotics early on could lead to obesity later in life, say scientists
Children given antibiotics before they were six months were 22% more likely to be overweight by the age of three
10:45 GMT, 21 August 2012
Treating babies with antibiotics risks making them overweight as they grow up, say scientists.
A study of more than 11,000 British children found those given the drugs before they were six months old had a bigger BMI (body mass index) than their peers.
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Antibiotics are often given to babies on a medicine spoon
But those given antibiotics between the age of six and 14 months did not have significantly higher body mass than children who did not receive any in that period.
Prof Leonardo Trasande, of New York University, said: 'We typically consider obesity an epidemic grounded in unhealthy diet and exercise, yet increasingly studies suggest it's more complicated.
'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.'
The study found on average babies given antibiotics from birth to five months weighed more for their height.
Between the ages of 10 to 20 months, this translated into small increases in body mass after taking into account impacts of diet, physical activity and parental obesity.
Prof Trasande and Prof Jan Blustein said the study published online in the International Journal of Obesity does not prove antibiotics in early life causes young children to be overweight.
It only shows a correlation exists and further studies will need to be conducted to explore the issue of a direct causal link.
In recent years there has been a growing concern about the overuse of antibiotics especially in children.
Preliminary studies implicate obesity, inflammatory bowel disease, asthma and other conditions with changes in the the trillions of microbial cells inhabiting our bodies – known as the microbiome – that outnumber our own cells ten to one.
But it's still a field in its infancy and no one has yet proved altering the composition of bacteria in the body leads to disease.
It is the first study that has analysed the association between the use of antibiotics and BMI 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 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.
The researchers analysed data from birth to 5 months of age, 6 to 14 months and finally from 15 to 23 months.
They also examined body mass or weight at five different points of time – six weeks, 10 months, 20 months, 38 months and seven years of age.
Antibiotic use only appeared to have an effect in very young infants.
Although children exposed to antibiotics at 15 to 23 months had somewhat greater BMI for their age and gender by the age of seven there was no significant increase in their being overweight or obese.
Prof Blustyein said: 'For many years now farmers have known antibiotics are great at producing heavier cows for market.
'While we need more research to confirm our findings this carefully conducted study suggests antibiotics influence weight gain in humans – and especially children too.'