Effects of promoting increased duration and exclusivity of breastfeeding on adiposity and insulin-like growth factor-I at age 11.5 years : a randomized trial

Martin, Richard M. and Patel, Rita and Kramer, Michael S. and Guthrie, Lauren and Vilchuck, Konstantin and Bogdanovich, Natalia and Sergeichick, Natalia and Gusina, Nina and Foo, Ying and Palmer, Tom and Rifas-Shiman, Sheryl L. and Gillman, Matthew W. and Davey Smith, George and Oken, Emily (2013) Effects of promoting increased duration and exclusivity of breastfeeding on adiposity and insulin-like growth factor-I at age 11.5 years : a randomized trial. Journal of the American Medical Association, 309 (10). pp. 1005-1013. ISSN 0098-7484

Abstract

IMPORTANCE: Evidence that increased duration and exclusivity of breastfeeding reduces child obesity risk is based on observational studies that are prone to confounding. OBJECTIVE: To investigate effects of an intervention to promote increased duration and exclusivity of breastfeeding on child adiposity and circulating insulin-like growth factor (IGF)-I (which regulates growth). DESIGN: Cluster-randomized controlled trial. SETTING: 31 Belarusian maternity hospitals and their affiliated polyclinics, randomized to usual practices (n=15) or a breastfeeding promotion intervention (n=16). PARTICIPANTS: 17,046 breastfeeding mother-infant pairs enrolled in 1996/7, of whom 13,879 (81.4%) were followed-up between January 2008 and December 2010 at a median age of 11.5 years. INTERVENTION: Breastfeeding promotion intervention modeled on the WHO/UNICEF Baby Friendly Hospital Initiative. MAIN OUTCOME MEASURES: Body mass index (BMI), fat and fat-free mass indices (FMI and FFMI), percent body fat, waist circumference, triceps and subscapular skinfold thicknesses, overweight and obesity, and whole-blood IGF-I. Primary analysis was based on modified intention-to-treat (without imputation), accounting for clustering within hospitals/clinics. RESULTS: The experimental intervention substantially increased breastfeeding duration and exclusivity (43% vs. 6% and 7.9% vs. 0.6% exclusively breastfed at 3 and 6 months, respectively) versus the control intervention. Cluster-adjusted mean differences in outcomes at 11.5 years between experimental vs. control groups were: 0.19 kg/m(2) (95% 4 CI: −0.09, 0.46) for BMI; 0.12 kg/m(2) (−0.03, 0.28) for FMI; 0.04 kg/m(2) (−0.11, 0.18) for FFMI; 0.47% (−0.11, 1.05) for % body fat; 0.30 cm (−1.41, 2.01) for waist circumference; −0.07 mm (−1.71, 1.57) for triceps and −0.02 mm (−0.79, 0.75) for subscapular skinfold thicknesses; and −0.02 standard deviations (−0.12, 0.08) for IGF-I. The cluster-adjusted odds ratio for overweight / obesity (BMI ≥85(th) percentile vs