Is metformin effective and safe during pregnancy in women with PCOS? An overview of reviews

Introduction: Metformin is a metabolic drug widely used in women with polycystic ovary syndrome (PCOS). It is effective for improving metabolic pattern and fertility, alone or combined with other treatments. Sparse data suggest that its administration before and during pregnancy may be also effective for reducing the PCOS-related pregnancy complications. Areas covered: Maternal, neonatal and offspring efficacy and safety of metformin administration in pregnant patients with PCOS. Expert opinion: A comprehensive literature search was conducted in March 2025 in PubMed, The Cochrane Library, and Web of Science databases using specific keywords related to metformin and PCOS. The search covered all articles published up to March 2025. Clinical evidence supports the efficacy of metformin in reducing the risk of preterm birth and pregnancy-induced hypertension in PCOS, but benefits for miscarriage or gestational diabetes mellitus (GDM) prevention are unclear. Notably, there is a lack of high-quality data on metformin as treatment for GDM or type 2 DM in PCOS pregnancies. Methodological differences and heterogeneous patient profiles limit clinical adoption. The use of metformin as strategy for preventing pregnancy complications in women with PCOS remains inconsistent due to limited consensus and concerns about long-term offspring safety.