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.
- 1. McCormick M. The contribution of low birth weight to infant mortality and childhood morbidity. N Engl J Med 1985; 312: 82-90.
- 2. Barker DJP. Mothers, babies and disease in later life. London: BMJ Publishing Group, 1994.
- 3. Read JS, Clements JD, Klebanoff MA. Moderate low birthweight and infectious disease mortality through infancy and childhood. Am J Epidemiol 1994; 140: 721-733.
- 4. Alessandri LM, Chambers HM, Garfield C, et al. Cumulative mortality in children aged 1 to 6 years born in Western Australia from 1980-89. Arch Dis Child 1999; 80: 15-20.
- 5. Freemantle CJ, Read AW, de Klerk NH, et al. Patterns, trends and increasing disparities in mortality for Aboriginal and non-Aboriginal infants born in Western Australia 1980–2001. Lancet 2006; 367: 1758-1766.
- 6. Northern Territory Department of Health. Maternal and infant mortality in the Northern Territory, 1974–1979. Issue no. 26. Darwin: Northern Territory Department of Health, 1980.
- 7. Australian Institute of Health and Welfare. Australia’s Health 2008. Australia's health no. 11. Canberra: AIHW, 2008. (AIHW Cat No. Aus 99.) http://www.aihw.gov.au/publications/index.cfm/title/10585 (accessed Nov 2009).
- 8. Hoy WE, Kondalsamy Chennakesavan S, Katz I. A chronic disease outreach program for Australian Aboriginal communities. Kidney Int 2005; 98: S76-S82.
- 9. Hoy WE, Kondalsamy-Chennakesavan S, Smith J, et al. The Aboriginal Chronic Disease Outreach Program. Submitted to Kidney Health Australia by the Centre for Chronic Disease, The University of Queensland, and Kidney Disease Research and Prevention. October 31 2004. http://www.healthinfonet.ecu.edu.au/health-resources/bibliography?lid=3289&ref=5 (accessed Nov 2009).
- 10. Singh GR, Hoy WE. The association between birthweight and current blood pressure: a cross-sectional study in an Australian Aboriginal community. Med J Aust 2003; 179: 532-535. <MJA full text>
- 11. Hoy WE, Kile E, Rees M, Mathews JD. Low birthweight and renal disease in Australian Aborigines. Lancet 1998; 352: 1826-1827.
- 12. Hoy WE, Wang Z, Baker PRA, et al. The natural history of renal disease in Australian Aborigines. Part 2. Albuminuria predicts natural death and renal failure. Kidney Int 2001; 60: 249-256.
- 13. Wang Z, Hoy WE. Albuminuria and incident coronary heart disease in Australian Aboriginal people. Kidney Int 2005; 68: 1289-1293.
- 14. Australian Bureau of Statistics. Trends in mortality by causes of death in Australia, the states and territories during 1971–92 and in the regions during 1991–92, 1971–92. Canberra: ABS, 1995. (Cat. No. 3130.0.) http://www.abs.gov.au/AUSSTATS/abs@.nsf/Prod uctsbyTopic/DBB5A2050F91EF3ACA25722E00 1A3A2E?OpenDocument (accessed Nov 2009).
- 15. Spencer JS, Silva DT, Snelling P, Hoy WE. An epidemic of renal failure among Australian Aborigines. Med J Aust 1998; 168: 537-541. <MJA full text>
- 16. World Health Organization. World health statistics 2009. Geneva: WHO, 2009.
- 17. Li Shu Q, Guthridge SL. Mortality in the Northern Territory, 1981–2000. Darwin: NT Department of Health and Community Services, 2004.
- 18. Thomas DP, Condon JR, Anderson IP, et al. Long-term trends in Indigenous deaths from chronic diseases in the Northern Territory: a foot on the brake, a foot on the accelerator. Med J Aust 2008; 185: 145-149. <MJA full text>
- 19. Condon JR, Barnes T, Cunningham J, Smith L. Improvements in Indigenous mortality in the Northern Territory over four decades. Aust N Z J Public Health 2004; 28: 445-451.
- 20. Hoy WE, Mathews JD, McCredie DA, et al. The multidimensional nature of renal disease: rates and associations of albuminuria in an Australian Aboriginal community. Kidney Int 1998; 54: 1296-1304.
- 21. Gogna NK, Smiley M, Walker AC, Fullerton P. Low birthweight and mortality in Australian Aboriginal babies at the Royal Darwin Hospital: a 15 year study. Aust Paediatr J 1986; 22: 281-284.
- 22. Sayers SM, Powers JR. Birth size of Australian Aboriginal babies. Med J Aust 1993; 159: 586-591.
- 23. Stanley FJ, Mauger S. Birth-weight patterns in Aboriginal and non-Aboriginal singleton adolescent births in Western Australia, 1979–83. Aust N Z J Obstet Gynaecol 1986; 26: 49-54.
- 24. Humphrey MD. Low Aboriginal birth weight, prematurity versus intrauterine growth restriction. Aust N Z J Obstet Gynaecol 1996; 36: 126-128.
- 25. Chan KN, Noble-Jamieson CM, Elliman A, et al. Lung function in children of low birthweight. Arch Dis Child 1989; 64: 1284-1293.
- 26. Wang Z, Hoy WE. Is the Framingham coronary heart disease absolute risk function applicable to Aboriginal people? Med J Aust 2005; 182: 66-69. <MJA full text>
- 27. Sayers SM, Powers J. Risk factors for Aboriginal low birthweight and intrauterine growth retardation and preterm birth in the Royal Darwin Hospital region. Aust N Z J Public Health 1997; 21: 524-530.
Publication of your online response is subject to the Medical Journal of Australia's editorial discretion. You will be notified by email within five working days should your response be accepted.