'Bigger the baby, the better' axiom is incorrect

May 17, 2007

Contrary to popular belief and alerts by the World Health Organization, new research by the George Institute for International Health indicates that the importance of the reported relationship between birth weight and coronary heart disease has been overestimated. Although low birth weight is considered by the WHO to be a risk factor for heart disease, the findings published today in the American Journal of Clinical Nutrition, question the widely held belief that smaller babies are more susceptible to heart disease later in life.

Dr Rachel Huxley, lead author of the paper and Acting Director of Nutrition and Lifestyle at The George Institute said, "Although there was support for a small association between birth weight and an individual's future risk of heart disease, the relationship is not as strong as earlier studies have suggested. Any effects that birth weight may have on heart disease are dwarfed by other risk factors operating in adult life, such as smoking and obesity."

Coronary heart disease is the leading cause of death in Australia, accounting for 38% of all deaths in 2002 and claiming the lives of more than one in three adults*. The study suggests that one kilogram higher birth weight is associated with a 10-20% reduced risk of heart disease later in life, compared to smaller sized babies. However, researchers believe that interventions during the pregnancy period would have little effect on increasing the size of a baby.

"It has been suggested that strategies to increase early fetal growth could reduce the number of deaths from heart disease. However, interventions during pregnancy could really only increase birth weight by as much as 100g, which would translate in to a 1-2% lower risk of heart disease." Dr Huxley added.

"By comparison, interventions that focus on getting individuals to make lifestyle changes such as quitting smoking, exercising and eating sensibly would substantially lower the risk of heart disease and are more achievable than strategies aimed at increasing birth weight."

Source: Research Australia