Association between gestational diabetes, ethnicity and migrant length of residence: An Australian cohort study

Investigate the relationship of gestational diabetes (GDM) risk for specific migrant groups compared to the Australian born of each ethnic group and length of residence (LOR) in Australia.

Retrospective observational cohort study from June 2020 to November 2023 at 10 Australian hospitals. Ethnicity was self-identified by participants. Log-binomial regression models were adjusted for confounding factors. Relative risk (RR) was determined for GDM by both ethnicity and duration of residency.

There were 60,701 participants, 32,391 (53.4%) were Australian born with South Asian the highest reported ethnic group (18.3%, n = 11,121). Women who migrated ≥5 years ago made up 31.8% (n = 19,282) of the cohort. GDM prevalence was 18.2% (n = 11,076). The recent migrant GDM rate was 2068/9028 (22.9%), LOR ≥5 years migrants were 4835/19,282 (25.1%) with Australian born 4173/32391 (12.9%). The adjusted relative risk (aRR) for GDM in migrants with an LOR <5 years was 1.37 (95%CI 1.31-1.43) when compared to Australian born. Among the ethnic groups, Middle Eastern women with LOR <5 years had the highest risk for GDM compared to those from the same ethnic group born in Australia (aRR 1.86; 95%CI 1.84-1.88).

This study identifies that the most ethnic migrant groups were at a higher risk of GDM than those of the same ethnicity born in Australia and this higher risk of GDM continued over time. Recognising migration effects may improve targeted and meaningful interventions to reduce GDM risk.