Children who were breastfed may be less likely to be overweight than their bottle-fed peers, and most of that benefit can be attributed to less weight gain in infancy, a study suggests.

Researchers in the Netherlands found that among more than 2,300 children followed from birth to age 7, those who were breastfed for more than 16 weeks generally had a lower body mass index (BMI) at the age of 1.

Similarly, these children had a lower average BMI and were less likely than their peers to be overweight by age 7. However, when the researchers considered other factors, including BMI at age 1, the link between breastfeeding and later-childhood weight faded.

A number of studies have investigated whether breastfeeding affects weight later in childhood, with conflicting findings. The current report suggests that breastfeeding may have lasting effects on children’s weight, but it’s by tempering weight gain in the first year of life.

“We showed in our study that the preventive effect of breastfeeding on overweight was already established at 1 year of age,” explained lead study author Salome Scholtens at the National Institute for Public Health and the Environment in Bilthoven.

“Breastfed children had a lower weight gain in the first year of life and therefore a lower overweight risk at 7 years of age,” Scholtens told Reuters Health.

This effect on weight gain in infancy may essentially put children on a “favorable ‘BMI track’,” the researchers conclude in a report published in the current issue of the American Journal of Epidemiology.

The findings are based on data from 2,347 children whose mothers were recruited during pregnancy to take part in an allergy prevention study. As part of that project, mothers reported on their breastfeeding practices, and the children’s BMI - a measure of weight in relation to height - was assessed periodically.

Many factors other than breastfeeding affect a child’s weight, Scholtens pointed out, and these factors - overall diet and exercise being chief ones - become more important as a child grows older.

It’s important for parents, whether they breastfeed or not, to teach their children healthy eating habits from an early age, according to Scholtens. “Parents play a crucial role in their child’s food acceptance and the development of a healthy dietary pattern.”

SOURCE: American Journal of Epidemiology, April 15, 2007.