Pregnancy outcomes in Type 2 versus Type 1 Diabetes: Systematic Review with Meta-analyses.

Objective: Increasing numbers of pregnancies are complicated by pregestational diabetes mellitus, especially type-2 diabetes. Some studies have reported similar or greater risk of adverse pregnancy outcomes among women with type-2 diabetes (T2DM) relative to type 1 diabetes (T1DM). We aimed to compare the risk of four pregnancy complications: pre-eclampsia, preterm delivery, macrosomia, and perinatal mortality, in pregnant women with T2DM versus T1DM in high-income countries.

Design: Systematic review with meta-analyses.

Methods: Systematic literature searches in Medline and Embase were performed. We included observational studies with original data of outcome occurrence in both women with pregestational T2DM and T1DM. Two researchers independently evaluated full-text studies for inclusion and assessed risk of bias using the Newcastle-Ottawa scale. Finally, we performed four meta-analyses.

Results: We included 35 publications in total. Meta-analyses demonstrated that, compared to T1DM, having T2DM was associated with lower risk of pre-eclampsia (risk ratio 0.76; 95% CI: 0.68-0.85), preterm delivery (risk ratio 0.69; 95% CI: 0.62-0.77) and macrosomia (risk ratio 0.75; 95% CI: 0.60-0.94). Perinatal mortality was more likely in pregnancies with T2DM (risk ratio 1.26; 95% CI: 1.06-1.50).

Conclusion: Summation of the research literature demonstrated that, compared to T1DM, women with T2DM had lower risk of pre-eclampsia, preterm delivery and macrosomia, and higher risk of perinatal mortality.