RISK-FACTORS FOR ABORIGINAL LOW-BIRTH-WEIGHT, INTRAUTERINE GROWTH-RETARDATION AND PRETERM BIRTH IN THE DARWIN HEALTH REGION

Risk factors for Aboriginal low birthweight (<2500 g), preterm birth ( <37 weeks' gestation) and intrauterine growth retardation (under the t enth percentile of Australian birthweights for gestational age) were e xamined in 503 live-born singletons recorded as born to an Aboriginal mother and routinely delivered at the Royal Darwin Hospital between Ja nuary 1987 and March 1990. Infants born to mothers with body mass inde x less than 18.5 kg/m(2) had five times the risk of hating low birthwe ight and 2.5 times the risk of intrauterine growth retardation. Popula tion-attributable risk percentages suggest that 28 per cent of low bir thweight and 15 per cent of growth retardation could be attributed to maternal malnutrition. Risk percentages for maternal smoking of more t han half a packet of cigarettes a da) were 18 per cent for low birthwe ight and 10 per cent for growth retardation. For growth retardation, 1 8 per cent could be attributed to a maternal age under 20 years. Risk factors for preterm birth were predominantly obstetric: the population -attributable risk percentage for pregnancy-induced hypertension was 2 6 per cent and for other obstetric conditions was 16 per cent. For Abo riginal births in the Darwin Health Region, maternal malnutrition and smoking are key elements in the prevention of low birthweight and intr auterine growth retardation. Teenage pregnancy is an important risk fo r intrauterine growth retardation, and pregnancy-induced hypertension is a risk for preterm birth.