Socioeconomic status, maternal risk factors, and gestational diabetes mellitus

Abstract Background While GDM incidence increases with rising living standards globally, within populations, women of lower socioeconomic status often face a higher risk-potentially due to uneven distribution of maternal risk factors. We aimed To evaluate the degree to which socioeconomic differences in gestational diabetes mellitus (GDM) are accounted for by differences in maternal risk factors, to assess whether age-related risks of GDM differ across socioeconomic groups, and to identify priority populations for future interventions. Methods We performed a register-based study using data from the Finnish Medical Birth Register and Statistics Finland on the 474 166 women who gave birth in Finland from 2008 to 2015. We collected information on GDM based on the International Classification of Diseases 10th Revision codes O24.4 and O24.9. We used multivariable models to examine the association between socioeconomic status, maternal risk factors, and GDM. We further tested interaction on multiplicative and additive scales. Results The incidence of GDM was 8.7% in 2008-2011 and 12.5% in 2012-2015. Lower socioeconomic levels than upper level employees were associated with an increased risk of GDM. Up to 64.0% of socioeconomic differences in GDM were attributed to body mass index and 5.5% to smoking. There was evidence for effect modification. Relative to women in the upper level category who were aged less than 19 years, GDM adjusted ORs (95% CIs) for women 35 years or older in upper level versus long-term unemployed groups were 3.28 (2.08-5.18) and 5.29 (3.35-8.35), respectively. Conclusions There is a paradox that socioeconomic advantage increases the incidence of GDM at the population level while reducing the incidence of GDM within the population. Nevertheless, socioeconomic differences in GDM persist and widen with increasing maternal age, even after accounting for maternal risk factors. Key messages • Obesity and smoking explained part of the socioeconomic differences in GDM, yet disparities widened with increasing maternal age. • Targeted interventions are needed for lower socioeconomic groups, particularly older women, to address within-population inequalities.