The impact of educational attainment on the occurrence of gestational diabetes mellitus in two successive pregnancies of Finnish primiparous women: a population-based cohort study.

Aims: To assess the impact of educational attainment on the occurrence and recurrence of gestational diabetes mellitus (GDM) in two successive pregnancies in primiparous women.

Methods: This is a population-based observational cohort study including all 2347 Finnish women without previously diagnosed diabetes, aged ≥ 20 years from the city of Vantaa, Finland, who gave birth to their first and second child between 2009 and 2015. National registries provided data on study participants. We divided the population into four groups according to the presence of GDM in the two pregnancies (GDM-/-, n = 1820; GDM-/+, n = 223; GDM+/-, n = 113; GDM+/+, n = 191).

Results: The occurrence of GDM in the first pregnancy was 13.0% (n = 304) and 17.6% (n = 414) in the second. The recurrence rate of GDM was 62.8%. The four groups did not differ in relation to educational attainment (p = 0.11). In multinomial regression analysis, educational attainment protected from GDM in the second pregnancy [relative risk ratio 0.93 (95% confidence interval (CI) 0.86-0.99) per year of schooling for being GDM-/+ compared with GDM-/-]. In multivariate logistics models, prepregnancy body mass index at the first pregnancy [odds ratio (OR) 1.53 per 1-standard deviation (SD) (95% CI 1.22-1.91)], first-born birth weight z-score [OR 1.30 per 1-SD (95% CI 1.00-1.67)], and inter-pregnancy weight change [OR 1.66 per 1-SD (95% CI 1.27-2.16)], but not educational attainment, predicted recurrence of GDM.

Conclusions: The recurrence rate of GDM was high. Education protected from novel GDM in the second pregnancy, but was not associated with GDM recurrence.