Oral Presentation International Association of the Diabetes and Pregnancy Study Groups 2022 - Hosted by ADIPS

Overweight/obesity and other predictors of gestational diabetes among Aboriginal and non-Aboriginal women in Western Australia (#38)

Marwan Ahmed 1 2 , Helen D Bailey 2 3 , Gavin Pereira 4 5 6 , Scott W White 7 8 , Kingsley Wong 2 4 , Rhonda Marriott 9 , Matthew J.L Hare 10 11 , Carrington CJ Shepherd 2 3 9
  1. School of Population and Global Health, The University of Western Australia, Perth, Australia
  2. The University of Western Australia (Telethon Kids Institute), Perth, WA, Australia
  3. Curtin Medical School, Faculty of Health Sciences, Curtin University, Perth, Australia
  4. Curtin School of Population Health, Curtin University, Perth, Western Australia, Australia
  5. Centre for Fertility and Health (CeFH), Norwegian Institute of Public Health, Oslo, Norway
  6. enAble Institute, Curtin University, Perth, Western Australia, Australia
  7. Division of Obstetrics and Gynaecology, The University of Western Australia, Perth, WA, Australia
  8. Maternal Fetal Medicine Service, King Edward Memorial Hospital, Subiaco, WA, Australia
  9. Ngangk Yira Research Centre, Murdoch University, Perth, WA, Australia
  10. Wellbeing and Chronic Preventable Diseases Division, Menzies School of Health Research, Charles Darwin University, Darwin, NT, Australia
  11. Department of Endocrinology, Royal Darwin Hospital, Darwin, NT, Australia

Background

Australian Aboriginal and Torres Strait Islander (hereafter respectfully called Aboriginal) women have a heavy burden of gestational diabetes (GDM) and of its main modifiable risk factor, overweight/obesity. However, the relationship between GDM and overweight/obesity has not been sufficiently studied within an Aboriginal context. This study aimed to investigate the predictors of GDM and the association between GDM and body mass index (BMI) in Aboriginal mothers.

Methods

We conducted a population-based retrospective cohort study that included all singleton births in Western Australia between 2012-2015 (n=133,215), using population health datasets linked by the Western Australian Data Linkage Branch. GDM status was ascertained from Midwives’ Notification System and Hospital Morbidity Data Collection datasets. Associations between GDM and its predictors were estimated as relative risks (RRs) and 95% confidence intervals (CI) from multivariable generalised linear models. Ratio of relative risks (RRRs) compared RRs in the Aboriginal and non-Aboriginal mothers. Adjusted population attributable fractions estimated the contribution of overweight/obesity to GDM burden, and adjusted predicted probabilities for GDM were plotted against BMI levels.

Results

About 8.8% of Aboriginal (9.2% of non-Aboriginal) pregnancies were complicated by GDM. The following predictors had stronger associations with GDM in Aboriginal mothers than in non-Aboriginal mothers: maternal obesity (defined as BMI≥30) (RR: 3.16, 95% CI: 2.54-3.93; RRR: 1.57, 95% CI: 1.26-1.94), previous LGA (RR: 1.70, 95% CI: 1.37-2.12; RRR: 1.41, 95% CI: 1.13-1.76) and previous macrosomia (RR: 1.55, 95% CI: 1.24-1.94; RRR: 1.53, 95% CI: 1.22-1.91). About 48.5% (95% CI: 39.7%-56.0%) of GDM cases in the Aboriginal population (23.7% in non-Aboriginal mothers, 95% CI: 21.9%-25.4%) were attributed to overweight/obesity. Compared to non-Aboriginal mothers, the adjusted probabilities of GDM among Aboriginal mothers were higher at all BMI levels, and showed greater increase with BMI.

Conclusion

Overweight and obesity are key drivers of GDM among Aboriginal women. The stronger association between BMI and GDM among Aboriginal women compared to non-Aboriginal women may relate to differences in body fat distribution. Developing strategies in partnership with Aboriginal community members to optimise weight pre-conception (and across the life course) should be prioritised.