Effects of promoting longer-term and exclusive breastfeeding on adiposity and insulin-like growth factor-I at age 11.5 years: a randomized trial
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Published on: February 15, 2018
Richard M Martin1, Rita Patel, Michael S Kramer
1School of Social and Community Medicine, University of Bristol, Bristol, England. richard.martin@bristol.ac.uk
Insights
A breastfeeding promotion intervention successfully increased breastfeeding duration and exclusivity but did not prevent childhood overweight or obesity at 11.5 years. These findings suggest population strategies to increase breastfeeding may not curb the obesity epidemic.
Area of Science:
- Pediatrics
- Public Health
- Nutrition
Background:
- Observational studies suggest longer-term and exclusive breastfeeding reduce child obesity risk, but are prone to confounding.
- Investigating the causal link between breastfeeding duration/exclusivity and child adiposity is crucial for public health strategies.
- Insulin-like growth factor I (IGF-I) plays a role in growth and may be influenced by breastfeeding, potentially impacting long-term adiposity.
Purpose of the Study:
- To assess the impact of a breastfeeding promotion intervention on child adiposity and IGF-I levels.
- To determine if increased breastfeeding duration and exclusivity prevent childhood overweight and obesity.
- To evaluate the effect of breastfeeding promotion on circulating IGF-I in children.
Main Methods:
- A cluster-randomized controlled trial involving 17,046 mother-infant pairs across 31 Belarusian maternity hospitals.
- Intervention group received breastfeeding promotion based on the WHO/UNICEF Baby-Friendly Hospital Initiative; control group received usual care.
- Follow-up at a median age of 11.5 years included measurements of BMI, fat mass indices, percent body fat, waist circumference, skinfold thickness, and whole-blood IGF-I.
Main Results:
- The intervention significantly increased breastfeeding duration and exclusivity (e.g., 43% vs 6% exclusively breastfed at 3 months).
- No significant differences were observed in BMI, fat mass indices, percent body fat, or waist circumference at 11.5 years.
- Odds ratios for overweight/obesity (BMI ≥ 85th percentile) were 1.18 and for obesity (BMI ≥ 95th percentile) were 1.17 in the intervention group compared to control, with overlapping confidence intervals.
Conclusions:
- A successful breastfeeding promotion intervention did not prevent overweight or obesity in children at 11.5 years.
- The intervention did not significantly affect IGF-I levels at follow-up.
- While breastfeeding offers numerous benefits, population-level strategies to increase its duration and exclusivity may not be effective in combating the childhood obesity epidemic.
Importance:
Evidence that longer-term and exclusive 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, Setting, And Participants:
Cluster-randomized controlled trial in 31 Belarusian maternity hospitals and their affiliated clinics, randomized into 1 of 2 groups: breastfeeding promotion intervention (n = 16) or usual practices (n = 15). Participants were 17,046 breastfeeding 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.
Intervention:
Breastfeeding promotion intervention modeled on the WHO/UNICEF Baby-Friendly Hospital Initiative (World Health Organization/United Nations Children's Fund).
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 and clinics.
Results:
The experimental intervention substantially increased breastfeeding duration and exclusivity when compared with the control (43% vs 6% exclusively breastfed at 3 months and 7.9% vs 0.6% at 6 months). Cluster-adjusted mean differences in outcomes at 11.5 years of age between experimental vs control groups were: 0.19 (95% CI, -0.09 to 0.46) for BMI; 0.12 (-0.03 to 0.28) for FMI; 0.04 (-0.11 to 0.18) for FFMI; 0.47% (-0.11% to 1.05%) for percent body fat; 0.30 cm (-1.41 to 2.01) for waist circumference; -0.07 mm (-1.71 to 1.57) for triceps and -0.02 mm (-0.79 to 0.75) for subscapular skinfold thicknesses; and -0.02 standard deviations (-0.12 to 0.08) for IGF-I. The cluster-adjusted odds ratio for overweight/obesity (BMI ≥ 85th vs <85th percentile) was 1.18 (95% CI, 1.01 to 1.39) and for obesity (BMI ≥ 95th vs <85th percentile) was 1.17 (95% CI, 0.97 to 1.41).
Conclusions:
AND RELEVANCE Among healthy term infants in Belarus, an intervention that succeeded in improving the duration and exclusivity of breastfeeding did not prevent overweight or obesity, nor did it affect IGF-I levels at age 11.5 years. Breastfeeding has many advantages but population strategies to increase the duration and exclusivity of breastfeeding are unlikely to curb the obesity epidemic.
Trial Registration:
isrctn.org: ISRCTN37687716; and clinicaltrials.gov: NCT01561612.
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