Disease in Transition – Louise Baur
Transitional Disease in Aboriginal Birth Cohort – Susan Sayers

Louise A Baur. Dept Paediatrics & Child Health, The University of Sydney, Australia

Impaired insulin action (insulin resistance) is a metabolic disturbance that is central to the development of a cluster of prevalent diseases including central obesity, heart disease, type 2 diabetes mellitus, various dyslipidaemias, hypertension and sleep apnoea. These disorders are now recognised to be of increasing public health importance in developing countries. Both genetic and environmental factors contribute to these diseases, which are recognised to have their origins in the intrauterine period, childhood and/or adolescence.

A global epidemic of overweight and obesity is now recognised. In 2000, 8.2% of the world’s adult population was estimated as being obese (of whom 54% were from economies in transition or developing countries), with continuing rises in prevalence expected. This is associated with a projected 250% increase in type 2 diabetes over the 25 years from 2000 to 2025 (estimated 100 million affected people in developed countries vs 228 million in developing countries). This is not just an adult phenomenon: obesity in childhood and adolescence is increasingly prevalent and type 2 diabetes is emerging as a disease of adolescence.

Susan Sayers. Menzies School of Health Research Darwin, Australia

In 1987 an Aboriginal Birth Cohort Study was commenced with the aims of describing Aboriginal birth size by weight, length and gestation age to investigate the influences of perinatal outcomes on childhood morbidity, growth and nutrition. These aims were later expanded to include potential markers of adult diseases in childhood. 1238 live born singletons were born in the Royal Darwin Hospital between January 1987 and March 1990 to mothers who were recorded as Aboriginal in the Delivery Suite Register. The 504 routine deliveries from the Darwin Health Region who had a post-natal gestational age estimation, had a mean birth weight 3085 grams ± SD600grams with a mean gestational age 39 weeks. 13.8 % were LBW (<2500grams), 7% were preterm (<37 weeks) and 25% were small for gestational age (SGA) ( Guaran et al.1994). Between December 1998 and 2001 the children of the cohort have been traced and anthropometric measures have been taken according to standard procedures and fasting blood glucose, serum insulin, total cholesterol, LDL-cholesterol, HDL-cholesterol and triglycerides have been measured. Five children died before the 10-13 year cross-sectional follow-up. To date there is an 87% follow up of living children with no significant differences in birth weight, sex ratio and gestational age between those not yet assessed and those assessed.

Preliminary results at cross sectional follow-up: The mean age was11.4 years, 50% were male and 34% had commenced puberty. The mean weight was 35kg, mean height 143cm and the mean BMI was 16.8kg/m². Overall, 10% were classified overweight (Cole et al.), 3.4% obese and 6.4% were stunted (HAZ<-2). Although there were no significant differences in mean age, puberty status and sex ratio, there were significant differences in growth and nutrition between urban (92) and rural (311) children. There were no stunted children (HAZ -2.0) in the urban group, 20% were classified overweight and 7.7% obese. For rural children 8.7% were stunted with 5.8% overweight and 1.6% obese. For overweight children measures of waist circumference, mid upper arm circumference, percent body fat and scapular/triceps skin fold ratio were significantly greater and the proportions of metabolic risk factors were significantly higher than those for children with a BMI below the overweight cut-off.  In this cohort children born greater then the 10^th percentile of weight for gestational age were more likely to be overweight than those who were SGA.

Conclusions: These preliminary findings show some overweight Aboriginal children (mean age 11.4 years) are already showing risk factors for chronic disease in adult life.

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2. Miller H and Hassanein K 1971 Diagnosis of impaired fetal growth in newborn infants.
3. Pediatrics 48:511-522.
4. Cole TJ, Bellizi MC, Flegal KM and Dietz WH. 2000 Establishing a standard definition for child overweight and obesity worldwide: international survey. British Medical Journal 320:1240-1243