Bigger babies are not guaranteed to grow into healthier adults when it comes to cholesterol levels and related heart disease problems, a study has found. The finding, based on studies covering more than 74,000 people worldwide, is the latest report to question a theory that enhanced nutrition during pregnancy leads to bigger birth weights that protect against a variety of later-life ills, the authors said.

The researchers Australia?s University of Sydney and at Oxford University and St George?s Hospital said on Tuesday they found cholesterol levels only fractionally higher in adults who were light at birth compared to adults who were heavy babies. In the United States in 2001 the average birth weight was 7.6 pounds (3.4 kg), a figure that has not changed markedly since at least 1970. Tuesday?s report, an analysis of more than 70 existing studies, did not detail what constituted heavy birth weights in those studied.

?While good maternal nutrition during pregnancy is clearly important, there is little evidence to suggest that size at birth is a risk factor for later disease in adult life,? said Rachel Huxley, of the George Institute at the University of Sydney, the chief author of the report. ?What matters most is how we choose to live now. Eating well, exercising and not smoking are key to a long and healthy life,? she added in the report published in this week?s Journal of the American Medical Association. Huxley published previous research in the Lancet in 2002, which, she said, disproved a link between birth weight and high blood pressure problems later in life.