Hildén K, et al. - In this large, population-based cohort study in Sweden, researchers assessed the interaction effects of gestational diabetes (GDM) with obesity on perinatal outcomes. Between 1998 and 2012, women without pre-gestational diabetes with a singleton birth were excluded. In addition to prematurity, the impact of maternal excess weight on adverse perinatal outcomes was not significantly different between the offspring of mothers with and without GDM. Major independent risk factors for most serious adverse perinatal outcomes were higher BMI and GDM. Investigators found that offspring of women with GDM had increased risk of malformations, prematurity, fetal distress and Erb's palsy, however, the risks of stillbirth and perinatal mortality were similar with the risks in the reference population. For the results studied, there is no interaction effect between GDM and BMI. Among women with either GDM or high BMI, more effective pre-pregnancy and antenatal interventions are needed to prevent serious adverse pregnancy outcomes.