RESUMO
AIMS: Findings concerning the impact of socio-economic status on the risk of gestational diabetes mellitus (GDM) are inconclusive and little is known about the simultaneous impact of income and educational attainment on the risk of GDM. This study aims to assess the impact of maternal prepregnancy income in combination with traditional GDM risk factors on the incidence of GDM in primiparous women. METHODS: This is an observational cohort study including 5962 Finnish women aged ≥ 20 years from the city of Vantaa, Finland, who delivered for the first time between 2009 and 2015, excluding women with pre-existing diabetes mellitus. The Finnish Medical Birth Register, Finnish Tax Administration, Statistics Finland, Social Insurance Institution of Finland and patient healthcare records provided data for the study. We divided the study population according to five maternal income levels and four educational attainment levels. RESULTS: Incidence of GDM decreased with increasing income level in primiparous women (P < 0.001 for linearity, adjusted for smoking, age, BMI and cohabiting status). In an adjusted two-way model, the relationship was significant for both income (P = 0.007) and education (P = 0.039), but there was no interaction between income and education (P = 0.52). CONCLUSIONS: There was an inverse relationship between both maternal prepregnancy taxable income and educational attainment, and the risk of GDM in primiparous Finnish women.