Growth & Development: Breastfeeding and Childhood Obesity

If infants who are breastfed for at least 12 months are slimmer than infants who are fed formula at 1 year of age, does this difference persist into childhood? Recent studies have attempted to answer this question.

Hediger and colleagues used data from the NHANES III (National Health and Nutrition Examination Survey) to study the rate of risk of overweight (85-94%tile BMI) or overweight (>95%tile BMI) in 2685 children age 3-5 years. Children had a reduced risk of being overweight if ever breastfed. However, the effect of breastfeeding on overweight was not statistically significant. The strongest predictor of a child being overweight was overweight or obesity in their mother ( Hediger, 2001 ).

A study by Gillman on 15,341 children age 9-14 years found that children who were fed only or mostly breast milk in the first 6 months of life had an OR of 0.78 (95% CI of 0.66-0.91) for being overweight(>95%tile BMI) compared to children who were only or mostly fed formula during this time. Secondly, infants who had been breastfed for 7 months or more had an OR of 0.80 (95% CI of 0.67-0.97) of being overweight compared to infants who had been breastfed less than 3 months ( Gillman, 2001 ).

A study of 33,768 children in the Czech republic found that being ever breastfed had an OR of 0.8 (95% CI 0.71-0.9) for being overweight (>90%tile BMI) and of 0.8 (95% CI 0.66-0.96) for being obese (>97%tile BMI) ( Toschke, 2002 ).

Evaluation of longitudinal data on over 170,000 children in the United States from the Pediatric Nutrition Surveillance System showed that increased duration of breastfeeding was associated with protection from obesity only in non-Hispanic white children ( Grummer-Strawn, 2004 ).

A meta-analysis of the effect of breastfeeding on the risk of obesity in later life, concluded that initial breastfeeding protects against obesity in later life, however there were many confounding variables ( Owen, 2005 ).

Kramer and coworkers in Belarus found no difference in overweight or obesity as measured by BMI, mid upper arm circumference and waist circumference in a group of infants randomized before birth and followed up until 6.5 years of age. Of the children in the experimental group 43.3% were exclusively breastfed for 3 months compared to 6.4% of children in the control group who were exclusively breastfed for the first 3 months of life. See also Growth of Breastfed Infants in the Developed World.

While all these studies attempted to control for life style differences such as TV watching, exercise, diet and parental size, the mechanisms for the decreased risk for later obesity in breastfed infants are not clear. A study by Taveras found that mothers who breastfed their infants for six months or longer were less likely to restrict their child's food intake when they were one year old. There was no relationship between breastfeeding and mothers' pressuring their one year old children to eat more. This may be one factor related to decreased obesity in later life in breastfed infants ( Taveras, 2004 ).