In research that included nearly 14,000 healthy infants in Belarus, an intervention that succeeded in improving the duration and exclusivity of breast-feeding during infancy did not result in a lower risk of overweight or obesity among the children at age 11.5.
Observational studies suggest that greater duration and exclusivity of having been breast-fed reduces child obesity risk, according to background information in the study, which appears in the March 13 issue of the Journal of the American Medical Association. “However, breast-feeding and growth are socially patterned in many settings,” the authors wrote, and observed associations between these variables are at least partly explained by confounding factors.
Richard M. Martin, PhD, of the University of Bristol (England), and colleagues investigated the effects of an intervention to promote increased duration and exclusivity of breast-feeding on child adiposity and circulating insulin-like growth factor 1, which regulates growth.
The randomized controlled trial was conducted in 31 Belarusian maternity hospitals and their affiliated clinics. Participants were randomized into one of two groups: breast-feeding promotion intervention or usual practices. Participants were 17,046 breast-feeding mother-infant pairs enrolled in 1996 and 1997, of whom 13,879 (81.4%) were followed up between January 2008 and December 2010 at a median age of 11.5 years.
The breast-feeding promotion intervention was modeled on the WHO/UNICEF Baby-Friendly Hospital Initiative. As previously reported, the researchers found that infants in the intervention group had substantially increased breast-feeding duration and exclusivity versus the control group. At three months, for example, more infants in the intervention group were exclusively (43.3% vs. 6.4%) and predominantly (51.9% vs. 28.3%) breast-fed. At six months, both exclusive (7.9% vs. 0.6%) and predominant breast-feeding (10.6% vs. 1.6%) were reduced, but more common in the intervention group. At 12 months, 19.7% (intervention) vs. 11.4% (control) were still breast-feeding to any degree.
At follow-up, when children were a median 11.5 years age, there were no significant differences between the experimental vs. control groups for the main outcomes, with cluster-adjusted average differences of 0.19 for body mass index; 0.12 for fat mass index; 0.04 for fat-free mass index; 0.47 for percent body fat; 0.30 centimeters for waist circumference; -0.07 mm for triceps and -0.02 mm for subscapular skinfold thicknesses; and -0.02 standard deviations for IGF-1.
“Among healthy term infants in Belarus, an intervention to improve the duration and exclusivity of infant breast-feeding did not prevent overweight or obesity, nor did it affect IFG-1 levels among these children [at age 11.5],” the authors concluded.
“Nevertheless, breast-feeding has many health advantages for the offspring, including beneficial effects demonstrated by our PROBIT trial on gastrointestinal infections and atopic eczema in infancy and improved cognitive development at age 6.5.
“Although breast-feeding is unlikely to stem the current obesity epidemic, its other advantages are amply sufficient to justify continued public health efforts to promote, protect and support it.”
The study abstract is available at http://jama.jamanetwork.com/article.aspx?articleid=1667089.