Myth: Using metformin during pregnancy causes birth defects.
Truth: This is false.
Metformin is an oral tablet that is used to treat high blood sugar levels caused by type 2 diabetes. Also, it is used to treat gestational diabetes and polycystic ovary syndrome. There has been an increase in the use of metformin during pregnancy within the last 10 years. Researchers in Ireland conducted a large study to determine if taking metformin during pregnancy causes birth defects. Over 50,000 babies with birth defects were involved in this study.
Researchers found that there is no increased risk of birth defects in babies exposed to metformin. There was one birth defect that was common, called pulmonary valve atresia which is a specific abnormality of the heart. However, this type of birth defect is associated with diabetes. For this reason, there is no definite link between pulmonary valve atresia and metformin. Read more about this study here.
- Given JE, Loane M, Garne E, et al.Metformin exposure in first trimester of pregnancy and risk of all or specific congenital anomalies: exploratory case-control study. BMJ. 2018. https://www.bmj.com/content/361/bmj.k2477