Breastfeeding - An Ongoing Debate

The US Department of Health and Human Services currently promotes breastfeeding as a strategy for reducing the risk of obesity in later life. They advise mothers that breastfeeding results in babies that are “less overweight” and who will “tend to gain less unnecessary weight.”

New research shows that this may not be the case and that there is no relationship between babies who were breastfed and later obesity in adulthood. Is it time to reassess the advice offered to mothers to help curb the obesity epidemic?

A review of research conducted during the last few years shows contradictory findings. Supporting the US Department of Health and Human Services point of view , studies from 2004 have claimed to show that breastfeeding children had a direct effect in the reduction of obesity rates. A meta-analysis by Rüdiger von Kries and colleagues compared nine studies looking at over 69,000 participants and concluded that breastfeeding had a “consistent effect against obesity in children”.

As well, in 2005 Andreas Plagemann and colleagues reviewed 17 studies to reveal a “dose-dependent association” between duration of breastfeeding and a decreased risk of obesity.

However, the latest study to show no link between breastfeeding and obesity was published in the International Journal of Obesity in April, 2007. Michele Forman and colleagues evaluated the weight of more than 35,000 nurses over twelve years by monitoring their Body Mass Index (BMI), a measure of weight relative to height. The authors then retrospectively assessed their diets in infancy by asking their mothers to fill out a four-page questionnaire detailing the type of milk their children were fed and the duration of breast and bottle feeding.

The study finds that, once socio-economic factors were removed from the analysis, breastfeeding was not associated with BMI after adolescence. The factors considered were those affecting both mother and nurse: maternal smoking during pregnancy, ownership of a home, the level of the mother’s and father’s education and the occupations of the nurse’s parents during her infancy and childhood were recorded and the results were adjusted to remove any effect they could have.

Furthermore, socio-economic factors affecting the nurse that were considered included her age at menarche – when she had her first period, how many children she has, whether she smokes, amount of physical activity, alcohol consumption, energy intake, menopausal status, her husband’s education and her household income.

Previous studies showing a link between breastfeeding and reduced rates of obesity in later life, and that support the advice of the US Department of Health and Human Services, often neglected to remove these confounding factors.