Nursing longer doesn’t protect against obesity, study says

Getting moms to nurse their babies longer and exclusively did not mean the kids were less at risk for obesity by the time they were 11-1/2 – despite suggestions from other studies that breastfeeding can protect against obesity, researchers in a large study from Belarus said.

The study, published Tuesday in the Journal of the American Medical Assn., included nearly 14,000 healthy babies in Belarus who were enrolled in the study in 1996 and 1997; researchers checked in over time, including when the children were an average of 11-1/2 years old.

In the randomized study, the babies were split into two groups, one of which breastfed longer. The other moms carried on as usual. In the intervention group, at 3 months, 43% were exclusively nursed, compared with 6.4% in the control group. At 1 year, the figures for children being nursed at all were almost 20% versus 11.4%.

Observational studies have suggested that nursing longer and exclusively could protect against obesity, but the researchers said that sort of study can have weaknesses that might affect results. For example, women who choose to breastfeed longer may be more educated than those who do not, and that could help explain what happens to kids later. Other social and environmental factors also could come into play, the researchers said.

“By randomizing, we can look at the long-term benefits of breastfeeding without the usual confounding present in observational studies because it wasn’t a choice for the mum,” the lead researcher, Richard M. Martin of the University of Bristol in England, said in an interview with JAMA.

Among the 11-year-old kids, there were no significant differences between the experimental and the control groups, the researchers said. They looked at such measures as body mass index, waist circumference and body fat percentages.

But there remain, the researchers said, plenty of benefits to breastfeeding.

“Based on our analysis of the intervention versus control arm, we found that those children in the intervention arm had a lower risk of gastrointestinal tract infections and atopic eczema in the first year of life. At 6.5 years of life, those in the breastfeeding arm had higher scores on IQ, so better cognitive development was seen in the breastfeeding group. The trial has provided strong evidence of these benefits,” Martin told JAMA.

The researchers are following the children into their teenage years to look at other potential health outcomes related to breastfeeding.