Major malformation risk, pregnancy outcomes, and neurodevelopmental outcomes associated with metformin use during pregnancy.

There are several reasons why metformin treatment may be considered for women in neuropsychiatric practice. These include prevention or attenuation of antipsychotic-associated weight gain, prevention or treatment of gestational diabetes mellitus (GDM), treatment of type 2 diabetes mellitus, and improvement of conception chances and pregnancy outcomes in the presence of polycystic ovarian disease (PCOD). This article examines the benefits and risks associated with metformin use during pregnancy. The available data suggest that metformin exposure during the first trimester is not associated with major congenital malformations; that metformin reduces the risk of early pregnancy loss, preeclampsia, preterm delivery, and GDM in women with PCOD; that metformin is associated with at least comparable benefits relative to insulin treatment in women with mild GDM; and that neurodevelopmental outcomes at age 1.5-2.5 years are comparable after gestational exposure to metformin and insulin. Whereas study designs were not always ideal and sample sizes were mostly small to modest, the study findings are more encouraging than discouraging and can guide shared decision-making in women who are receiving or may need metformin during pregnancy.