Low-educated women have an increased risk of gestational diabetes mellitus: the Generation R Study.

Aims: To investigate whether maternal educational level is associated with gestational diabetes mellitus (GDM), and to what extent risk factors for GDM mediate the effect of educational level.

Methods: We examined data of 7,511 pregnant women participating in a population-based cohort study in Rotterdam, the Netherlands. The highest achieved education was categorized into four levels. Diagnosis of GDM was retrieved from delivery records. Odds ratios (OR) of GDM were calculated for levels of education, adjusting for confounders and potential mediators. Mediators were selected according to Baron and Kenny's causal step approach.

Results: Adjusted for ethnicity, age, family history of diabetes and parity, women in the lowest educational level were three times more likely to develop GDM than women in the highest level (OR 3.07; 95 % CI 1.37, 6.89). Selected mediators were alcohol use and body mass index (BMI). Additional adjustment for alcohol use attenuated the OR to 2.54 (95 % CI 1.11, 5.78). The individual addition of BMI attenuated the OR to 2.35 (95 % CI 1.03, 5.35). All mediators together explained 51 % (95 % CI -122, -25) of the association between low education and GDM.

Conclusions: Low maternal educational level is associated with GDM, which is mainly due to higher rates of overweight and obesity. In order to reduce the higher rates of GDM, and consequently type 2 diabetes among women in low socioeconomic subgroups, prevention and intervention strategies need to be focused on reducing the rates of overweight and obesity before pregnancy.