Rönö K, et al. - In this observational cohort study, primiparous women were studied with regard to the effect maternal prepregnancy income combined with traditional gestational diabetes mellitus (GDM) risk factors has on the incidence of GDM. Study participants were 5,962 Finnish women aged ≥ 20 years from the city of Vantaa, Finland, who delivered for the first time between 2009 and 2015. Women with pre-existing diabetes mellitus were excluded from this analysis. An inverse relationship was found between both maternal prepregnancy taxable income and educational attainment, and GDM risk in primiparous Finnish women.