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Birthweight and natural deaths in a remote Australian Aboriginal community

Wendy E Hoy and Jennifer L Nicol
Med J Aust 2010; 192 (1): 14-19.

Summary

Objectives: To describe associations between birthweight and infant, child and early adult mortality from natural causes in a remote Australian Aboriginal community against a background of rapidly changing mortality due to better health services.

Design, participants and setting: Cohort study of 995 people with recorded birthweights who were born between 1956 and 1985 to an Aboriginal mother in a remote Australian Aboriginal community. Participants were followed through to the end of 2006.

Main outcome measures: Rates of natural deaths of infants (aged 0 to < 1 year), children (aged 1 to < 15 years) and adults (aged 15 to < 37 years), compared by birth intervals (1956–1965, 1966–1975 and 1976–1985 for infants and children, and 1956–1962 and 1963–1969 for adults) and by birthweight.

Results: Birthweights were low, but increased over time. Deaths among infants and children decreased dramatically over time, but deaths among adults did not. Lower birthweights were associated with higher mortality. Adjusted for birth interval, hazard ratios for deaths among infants, children and adults born at weights below their group birthweight medians were 2.30 (95% CI, 1.13–4.70), 1.78 (95% CI, 1.03–3.07) and 3.49 (95% CI, 1.50–8.09), respectively. The associations were significant individually for deaths associated with diarrhoea in infants, with cardiovascular and renal disease in adults, and marginally significant for deaths from pulmonary causes in children and adults.

Conclusion: The striking improvements in infant and child survival over time must be applauded. We confirmed a predisposing effect of lower birthweights on deaths in infants and children, and showed, for the first time, an association between lower birthweights and deaths in adults. Together, these factors are probably contributing to the current epidemic of chronic disease in Aboriginal people, an effect that will persist for decades. Similar phenomena are probably operating in developing countries.

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  • Wendy E Hoy1
  • Jennifer L Nicol2

  • Centre for Chronic Disease, School of Medicine, University of Queensland, Brisbane, QLD.

Correspondence: w.hoy@uq.edu.au

Acknowledgements: 

We thank the study community and their Land Council for their continued great interest and collaboration in the ongoing studies, now in their 21st year. John Mathews, then Director of the Menzies School of Health Research, encouraged exploration of the Barker hypothesis among the Aboriginal populations of the Northern Territory. Sister Maureen Carey and Alan Walker allowed and facilitated access to delivery and birthweight records, and Emma Kile documented and first analysed those birth records, in pursuit of her BMedSci. We thank the staff of the community’s clinics for access to clinical charts and death records, and Suresh Sharma, Hilary Bloomfield, Bernard Tipiloura, Hadley Tungutalum and other community liaison workers for constantly updating death records. Staff of the Menzies School of Health Research have contributed much administrative, laboratory, statistical and technical assistance over the years. Wendy Hoy was based at the Menzies School of Health Research during some of this work, and has a continuing honorary appointment there. Susan Mott has provided excellent administrative, technical and analytical help. Funding was provided by: National Health and Medical Research Council project grants (numbers 921134, 951342 and 320860), and The Colonial Foundation of Australia. Janssen Cilag of Australia, Amgen, Servier, Kidney Health Australia and Rio Tinto have also contributed support. The role of all funding bodies was solely the provision of funding.

Competing interests:

None identified.

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