We investigated whether ethnocultural inequality in rates of gestational diabetes was prevalent in Canada. We compared the Anglophone minority with the Francophone majority in Quebec. We conducted a retrospective cohort study of 853,595 pregnancies between 2008 and 2020 in Quebec, Canada. The exposure was ethnocultural status, with patients classified as either Anglophone or Francophone based on the maternal language. The outcome was gestational diabetes. We calculated risk ratios (RR) and 95% confidence intervals (CI) for the association between ethnocultural status and risk of gestational diabetes using log-binomial regression models adjusted for maternal age, parity, comorbidity, education, country of origin, material deprivation, urban residence, and time period. Anglophones had a higher rate of gestational diabetes compared with Francophones (99.0 vs 81.0 per 1000 pregnancies
RR 1.07, 95% CI 1.05-1.10). Anglophones aged less than 25 years (RR 1.31, 95% CI 1.21-1.41), living in rural areas (RR 1.73, 95% CI 1.64-1.82), lacking a high school diploma (RR 1.48, 95% CI 1.37-1.61), or with material disadvantage (RR 1.33, 95% CI 1.27-1.39) had greater risks of gestational diabetes compared with Francophones. Risk of gestational diabetes among Anglophones increased over time, especially among disadvantaged subgroups of the population. The findings suggest that the Anglophone ethnocultural minority in Quebec has an increasing risk of gestational diabetes over time compared with the Francophone majority. Risks are particularly elevated for Anglophones from disadvantaged subgroups of the population.