Breastfeeding May Not Control Childhood Weight

NEW YORK (Reuters Health) - There are many good reasons to breastfeed, but ensuring a healthy childhood weight may not be one of them, a new study suggests.

Australian researchers found that although 12-month-olds who were still being breastfed were leaner than other babies, the weight difference disappeared by the time the children were 8 years old.

In addition, there was no clear association between duration of breastfeeding and a child's risk of being overweight between the ages of 1 and 8. Children who were never breastfed had similar odds of becoming overweight as those who were breastfed for 4 to 12 months. And those who were never were less likely to be overweight than those breastfed for up to 4 months.

"Our data do not support a role for breastfeeding in weight control after infancy and up to the age of 8 years," the study's lead author, Dr. Valerie Burke of the University of Western Australia in Perth, told Reuters Health.

However, she added, it's still possible that breastfeeding is associated with a lower weight at older ages, and the current findings do not negate studies that have linked breastfeeding to healthier weights in adolescence and adulthood.

She said her group is now assessing the children's weights at age 13.

Some previous studies have found that children who'd been breastfed were less likely to be overweight than their bottle-fed peers. But it hasn't been clear that breastfeeding itself confers the benefit; one reason is that overweight and obese mothers are less likely to breastfeed, and a mother's weight is a strong factor in her children's weight.

In the new study, published in the Journal of Pediatrics, children who were breastfed for 4 months or less had the highest prevalence of overweight between the ages of 1 and 8. And their mothers had the highest prevalence of obesity and smoking, along with the lowest overall education level, suggesting a prime role for the family environment in children's excess weight.

The study included more than 2,000 children who were followed from early infancy through the age of 8. Each child's body mass index (BMI), a measure of weight in relation to height, was recorded at the ages of 3, 6 and 8; their weight and length were measured at age 1. The children were divided into groups based on whether, and for how long, they were breastfed.

Overall, children who were breastfed for more than 12 months were the leanest at the age of 1, but the difference between them and other children narrowed thereafter, until it was no longer evident at age 8.

Between the ages of 1 and 8, the average BMIs in the different breastfeeding groups tended to "converge," Burke and her colleagues report. And any differences among the groups were no longer significant when maternal factors, such as weight and education, were considered.

"It may be that family lifestyle factors outweigh any possible effect of breastfeeding on weight gain in childhood," Burke said.

She noted that her team's study differed in several ways from previous ones showing weight benefits from breastfeeding -- including direct measurements, rather than parents' reports, of the children's weights, as well as information on mothers' characteristics collected from pregnancy onward.

Burke stressed that regardless of the effect, or lack of effect, that breastfeeding has on a child's weight, it is still the best nutrition for an infant.

"There are so many other benefits of breastfeeding that we do not want our findings to be interpreted as a reason not to breastfeed."

SOURCE: Journal of Pediatrics, July 2005.