The dangers of low birth weight and later heart risk may have been over-estimated, according to a review by The George Institute for International Health in Sydney.

The study review found only a small association between birth weight and the future risk of heart disease. “We found a 1kg difference – going from 2.5kg to 3.5kg in birth weight – was associated with just a 10-15 per cent reduction in the risk of heart disease in later life,” says Dr Rachel Huxley, the study’s lead author. “Some reports have suggested a kilogram difference carriers a 25-40 per cent greater risk.”

Huxley says efforts to increase early foetal growth can change birth weight only by as much as 100g, which translates to just a 1-2 per cent lower risk of heart disease. Risk factors operating in later adult life, such as smoking and obesity, are more important, she says.