Association Between Metformin Use in Early Gestational or Type 2 Diabetes in Pregnancy and Preterm Preeclampsia.

Objective: To estimate the association between maternal metformin use for the treatment of early gestational or pre-existing type 2 diabetes and preterm preeclampsia.

Methods: This is a planned secondary analysis of the MOMPOD study (Medical Optimization of Management of Overt Type 2 Diabetes in Pregnancy), a randomized trial comparing the effect of adding metformin with insulin treatment on composite neonatal outcome in singleton pregnancies with early gestational or type 2 diabetes. Participants were randomized at 11-23 weeks of gestation to 1,000 mg metformin twice daily or placebo until delivery. A subset of participants had maternal blood collected at 24-30 weeks of gestation, and serum soluble endoglin, apolipoprotein B, vascular cell adhesion molecule-1, soluble fms-like tyrosine kinase 1, placental growth factor, high-sensitivity C-reactive protein, adiponectin, and vascular endothelial growth factor levels were measured. Our primary outcome was preterm preeclampsia , defined as preeclampsia requiring delivery before 37 weeks of gestation. Secondary outcomes included preterm preeclampsia requiring delivery before 34 weeks of gestation and differences in serum biomarkers. Multivariable regression analysis was used to estimate the associations between metformin use and primary or secondary study outcomes.

Results: Of 831 participants, 119 (14.3%) developed preeclampsia requiring delivery before 37 weeks of gestation: 57 of 416 (13.7%) in the placebo group and 62 of 415 (14.9%) in the metformin group. Thirty-seven (4.4%) developed preeclampsia requiring delivery before 34 weeks of gestation: 15 (3.6%) receiving placebo and 22 (5.3%) receiving metformin. Compared with placebo, metformin was not associated with a significant difference in the occurrence of preeclampsia before 37 weeks of gestation (adjusted odds ratio [aOR] 1.04, 95% CI, 0.70-1.56) or before 34 weeks (aOR 1.43, 95% CI, 0.73-2.81). Similarly, there was no association between maternal metformin use and serum biomarker levels.

Conclusion: Among parturients with early gestational or pre-existing type 2 diabetes, the addition of metformin to insulin was not associated with lower odds of preterm preeclampsia or with serum biomarkers associated with cardiovascular disease risk.