"There's a lot of other evidence out there to continue to support breast-feeding," says the study's lead author Dr. Richard Martin, a professor of clinical epidemiology at the University of Bristol in the U.K. "But in terms of breastfeeding reducing obesity, it's unlikely to be effective."
Martin worked with colleagues at Harvard University and McGill University in Montreal to assess 15,000 mothers in Belarus. The location was intentional — when the study began in 1996, breastfeeding was not a popular practice among Belarusian mothers. By separating the moms-to-be into two groups — one that gave birth at hospitals where staff received "Baby-Friendly" training designed to encourage breastfeeding, while the other delivered at hospitals that provided no extra support for the practice — researchers were able to create a "huge contrast" in a setting where breastfeeding rates were historically low. After three months, 43% of babies in the first group were exclusively breastfeeding compared to just 6% in the group that were born in hospitals that had no extra training.
The babies were followed up in 1997 — their first year of life — and again when they reached 6 ½ and 11 ½. The breastfed babies experienced fewer gastrointestinal infections, less eczema and higher IQ (they scored about 7 ½ points higher than their formula-fed friends at age 6 ½). There was no difference in dental cavities, allergies, asthma or rates of being overweight or obese.
The latest report, published in the Journal of the American Medical Association (JAMA) marks the first release of data from the 11 ½-year old participants. Mirroring the earlier results, the researchers found no changes in weight and body fat between those who were breast-fed and those who weren't. About 15% of the children in both groups were overweight, and 5% were considered obese.
Comparing body mass index (BMI) or measures such as waist circumference and skin thickness yielded "absolutely nothing that was statistically significant," says Martin.
Image: Breastfeeding mother and children, via Shutterstock