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Breast-feeding failed to prevent obesity, affect IGF-I levels
Previous studies have examined the association between breast-feeding and adiposity and later-life serum insulin-like growth factor. After using a breast-feeding promotion intervention in Belarus, researchers report an intervention that improved duration and exclusivity of breast-feeding did not prevent overweight or obesity. Findings also suggest it did not affect IGF-I levels at age 11.5 years.
Richard M. Martin, PhD, of the school of social and community medicine at the University of Bristol in England, and colleagues conducted a cluster-randomized control trial consisting of 31 Belarusian maternity hospitals and affiliated clinics.
Patients were randomly assigned to one of two groups: breast-feeding promotion intervention (n=16) or usual practices (n=15). This included breast-feeding mother-infant pairs enrolled in 1996 and 1997 (n=17,046); 81.4% (n=13,879) completed follow-up between January 2008 and December 2010 at the median age of 11.5 years, researchers wrote.
According to data, the breast-feeding promotion intervention (modeled on WHO/UNICEF Baby-Friendly Hospital Initiative) increased breast-feeding duration and exclusivity considerably compared with controls (43% vs. 6% exclusively breast-fed at 3 months and 7.9% vs. 0.6% at 6 months).
At age 11.5 years, further data indicate cluster-adjusted mean differences in outcomes between the interventions vs. control groups for BMI (0.19; 95% CI, −0.09 to 0.46); fat mass indices (0.12; 95% CI, −0.03 to 0.28); fat-free mass indices (0.04; 95% CI, −0.11 to 0.18); percent body fat (0.47%; 95% CI, −0.11 to 1.05); waist circumference (0.3 cm; 95% CI, −1.41 to 2.01); triceps (−0.07 mm; 95% CI, −1.71 to 1.57); and subscapular skinfold thicknesses (−0.02 mm; 95% CI, −0.79 to 0.75), with −0.02 standard deviations (95% CI, −0.12 to 0.08) for IGF-I.
Additionally, cluster-adjusted OR (BMI ≥85th vs. <85th percentile) was 1.18 (95% CI, 1.01-1.39) for overweight/obesity, and OR (BMI ≥95th vs. <85th percentile) was 1.17 (95% CI, 0.97-1.41) for obesity, researchers wrote.
“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 researchers wrote.
Disclosure: Martin reports presenting an invited talk for the Nestle Nutrition Institute.
Perspective
Back to TopThis longitudinal study has been in the works for many years. PROFIT (Promotion of Breastfeeding Intervention trial) was designed to examine the effects of longer-term and exclusive breastfeeding on growth and development using a randomized controlled trial in Belarus.
Of the many potential benefits of breastfeeding, this publication examines whether longer-term exclusive breastfeeding has a protective effect on obesity later in life in children.
The investigators earlier reported results of children aged about 6 years after the intervention and now this is another follow-up publication looking at the children aged 11 years. They have found that there was no evidence of a protective effect of breastfeeding on later obesity in these children.
This has been an unresolved controversy in our field for some time. Some studies show a positive protective effect and others have shown none. The difficulty with epidemiological studies in this area is that we ethically can’t randomize to breastfeeding or formula feeding.
Many of the studies which have compared breastfeeding to formula-feeding may have residual confounding effects. There may be unmeasured factors in a given study that may account for the differences seen between breast-fed and formula-fed infants later in life. Although researchers tried to capture many of the confounding variables, we recognize we can’t control for all influencing factors. There is always that lingering question to whether the finding was really due to residual confounding.
What is unique about PROFIT is that the women had to opt for breastfeeding from the very beginning. Therefore, this study is different than other studies where they have a formula feeding group and a breastfeeding group from birth. In PROFIT, the intervention was based on the WHO/UNICEF Baby-Friendly Initiative and resulted in a longer duration of exclusive breastfeeding and a longer duration of breastfeeding overall. The control group received usual healthcare in Belarus maternity clinics. PROFIT is one, if not the largest prospective study in this area, and had excellent participant retention. In this analysis, indicators of body adiposity and growth rate were examined. Specifically, body mass index (BMI), body fat and lean body mass using bioimpedance and the hormone IGF-1 by RIA or ELIZA were measured at age 6 years. The duration and exclusivity of breastfeeding did not affect these outcomes.