The Gomeroi gaaynggal cohort: a preliminary study of the maternal determinants of pregnancy outcomes in Indigenous Australian women

The life expectancy of Indigenous Australians is amongst the lowest of any population group within developed nations and chronic diseases collectively account for over 80% of the gap in life expectancy between Indigenous and non-Indigenous Australians. The Gomeroi gaaynggal cohort is a prospective, longitudinal maternal-infant cohort established to examine the origins of chronic disease in Indigenous Australians. This study aimed to determine the major antenatal factors associated with adverse birth outcomes (preterm delivery, low birth weight) and other pregnancy-related complications (gestational diabetes and hypertensive disorders of pregnancy) in Indigenous Australian women. Pregnant women who identified as Indigenous Australians or pregnant non-Indigenous women giving birth to an Indigenous infant were eligible to participate in the cohort (n=227). Physical measurements and biological sample collection (including blood and urine) were undertaken up to 3 times in pregnancy. Median weight and BMI of the cohort was 80.7 kg and 30.3 kg/m² at enrolment (median 23 weeks gestation). 43% reported smoking cigarettes during pregnancy. Of the 158 women in whom pregnancy outcomes were known, 43% had an uncomplicated pregnancy, 13.9% delivered preterm, 14.6% delivered a small-for-gestational age infant, 10% developed a hypertensive disorder of pregnancy, and 6.3% developed gestational diabetes. In addition, many women showed evidence of underlying renal dysfunction (proteinuria or albuminuria). The ratio of male to female offspring in this cohort was 1.38. Eighty-seven percent of preterm infants were male, as were 83.3% of babies from women with gestational hypertension. This skewed sex distribution was far higher than for those who had a healthy pregnancy outcome (59%). This study demonstrates that key factors including maternal obesity, exposure to cigarette smoke and underlying renal impairment, influence pregnancy outcome. Preliminary findings from this study also suggest that more male babies are born early and from complicated pregnancies in this Indigenous cohort.