Gestational diabetes and adiposity are independent risk factors for perinatal outcomes: a population based cohort study in Sweden

AIMS: To evaluate the interaction effects of gestational diabetes (GDM) with obesity on perinatal outcomes. METHODS: A population‐based cohort study in Sweden excluding women without pre‐gestational diabetes with a singleton birth between 1998 and 2012. Logistic regression was performed to evaluate the potential independent associations of GDM and BMI with adverse perinatal outcomes as well as their interactions. Main outcome measures were malformations, stillbirths, perinatal mortality, low Apgar score, fetal distress, prematurity and Erb's palsy. RESULTS: Some 1,294,006 women were included, with a GDM prevalence of 1% (n = 14,833). The rate of overweight/obesity was 67.7% in the GDM‐group and 36.1% in the non‐GDM‐group. No significant interaction existed. Offspring of women with GDM had significantly increased risk of malformations, adjusted odds ratio (aOR) 1.16 (95% confidence intervals 1.06–1.26), prematurity, aOR 1.86 (1.76–1. 98), low Apgar score, aOR 1.36 (1.10–1.70), fetal distress, aOR 1.09 (1.02–1.16) and Erb's palsy aOR 2.26 (1.79–2.86). No risk for stillbirth or perinatal mortality was seen. Offspring of overweight (BMI 25–29.9 kg/m(2)), obese (BMI 30–34.9 kg/m(2)) and severely obese women (BMI ≥ 35.0 kg/m(2)) had significantly increased risks of all outcomes including stillbirth 1.51 (1.40–1.62) to 2.85 (2.52–3.22) and perinatal mortality 1.49 (1.40–1.59) to 2.83 (2.54–3.15). CONCLUSIONS: There is no interaction effect between GDM and BMI for the studied outcomes. Higher BMI and GDM are major independent risk factors for most serious adverse perinatal outcomes. More effective pre‐pregnancy and antenatal interventions are required to prevent serious adverse pregnancy outcomes among women with either GDM or high BMI.