Is metformin safe in pregnancy: a focus on offspring outcomes

Metformin has been part of treatment algorithms for type 2 diabetes mellitus (T2DM) for decades. While it has formal approval in the U.S.A. for treatment of T2DM, it is used off-label in gestational diabetes mellitus (GDM), polycystic ovarian syndrome (PCOS), and ovarian hyperstimulation prevention. Its role as an insulin sensitizer has made it an attractive therapeutic to address the insulin resistance seen in these syndromes. In 2022, the European Union approved metformin as the only oral antidiabetic medication for diabetes in pregnancy. While its safety and benefits for the mother are well documented, it does cross the placenta with plasma concentrations comparable between mother and child at delivery.

This special report will focus on major randomized control trials investigating metformin use in pregnancies impacted by PCOS, GDM, T2DM, and obesity and their offspring follow-up trials.

For the mother, metformin can be beneficial, with reduction in insulin therapeutic burden, weight gain, hypoglycemia and in certain situations, pre-eclampsia. For the neonate, benefits may include reduction in hypoglycemia and no increased risk of congenital anomalies. It is the long-term data in the offspring that remains unknown with some areas of concerns (SGA, altered anthropometrics) requiring continued research.