Dramatically improved survival among infants of lower birthweights may be contributing to an epidemic of chronic diseases in the Australian Aboriginal population, according to the authors of a study published in the Medical Journal of Australia.
Professor Wendy Hoy, Professor of Medicine and Director of the Centre for Chronic Disease at the University of Queensland, and her co-author conducted a cohort study of 995 people born between 1956 and 1985, all with an Aboriginal mother and all born in a remote Aboriginal community. Birthweights were much lower than those in non-Aboriginal Australians.
Professor Hoy said there had been striking reductions in the rates of deaths of infants and children over three successive birth intervals (1956-65, 1966-75, 1976-85). This reduction operated across the entire birthweight spectrum. As a result, vastly more infants and children, including those of low birthweight, are surviving to reach adult life.
The study also found that the risk of natural deaths in infants, children and adults born at a weight below their group medians, (which were about 600 gm lower than current non-Aboriginal mean birthweights), were 2.30, 1.78 and 3.49 times greater than in those of higher birthweights. Lower birthweight were consistently associated with higher mortality for most causal categories of natural death.
The association of lower birthweights with higher mortality in infants and children is already well known, Professor Hoy said. However, this is the first demonstration in Australia of the association of lower birthweights with deaths in adults. Most of those adult deaths were due to chronic lung disease, cardiovascular disease and kidney disease, elements of the "chronic disease epidemic". "With lower mortalities in infancy and childhood, many more individuals born at lower birthweights are surviving to adult life. These adults are at higher risk of chronic diseases, consistent with the Barker hypothesis," Professor Hoy said. "Thus the epidemic of chronic disease in Aboriginal people appears to be a legacy, in part, of earlier therapeutic triumphs."
In an accompanying editorial in the MJA, Associate Professor Susan Sayers, Principal Research Fellow at the Menzies School of Health Research, and her co-author write that a key element in any preventive strategy for chronic disease associated with premature adult mortality is the prevention of overweight and obesity.
Professor Sayers said that preconception interventions were also needed to prepare the intrauterine environment for the developing fetus.
"Future research should be directed towards developing and evaluating culturally specific adaptations of this early care for young Aboriginal women of childbearing age," she said.
The Medical Journal of Australia is a publication of the Australian Medical Association.