Maternal Body Mass Index and Ethnicity in Relation to The Adverse Outcomes of Large for Gestational Age and Gestational Diabetes Mellitus in a Retrospective Cohort of Australian Pregnant Women.

Background: The prevalence of maternal overweight and obesity has been increasing. This research explored the association between maternal body mass index and ethnicity in relation to the adverse outcomes of large for gestational age and gestational diabetes mellitus. Method: A retrospective cohort study was undertaken with 27 814 Australian women of various ethnicities, who gave birth to a singleton infant between 2008 and 2017. Variables were examined using logistic regression. Results: A significantly higher proportion of large for gestational age infants were born to overweight and obese women compared to those who were classified as underweight and healthy weight. Asian-born women with a body mass index of ≥ 40kg/m 2 had an adjusted odds ratio of 9.926 (3.859 - 25.535) for birthing a large for gestational age infant whereas Australian-born women had an adjusted odds ratio of 2.661 (2.256 - 3.139) for the same outcome. Women born in Australia were at high risk of birthing a large for gestational age infant in the presence of insulin controlled gestational diabetes mellitus, but this risk was not significant for those with the diet-controlled type. Asian-born women did not present an elevated risk of birthing a large for gestational infant, in either the diet controlled, or insulin controlled gestational diabetes mellitus groups. Conclusion: Large for gestational age and gestational diabetes mellitus are adverse pregnancy outcomes that can lead to significant maternal and neonatal morbidity. Women who are overweight or obese, and considering a pregnancy, are encouraged to seek culturally appropriate nutrition and weight management advice during the periconception period.