Metformin in early pregnancy safe for fetus

Metformin taken by women with polycystic ovary syndrome (PCOS) during the first trimester of pregnancy does not appear to increase the risk of major fetal malformations, and may have a significant protective effect. Metformin is used, with or without insulin, to treat patients with type 2 diabetes - and it is also used to treat infertility in women with polycystic ovary syndrome. However, the safety of this drug for the fetus has not been established. Furthermore, a similar drug, phenformin, has been shown to cause birth defects. Polycystic ovary syndrome is caused by the disruption of the reproductive cycle. Features include enlarged ovaries studded with numerous cystic follicles that contain immature eggs; excess hair growth; and obesity. Women with polycystic ovary syndrome have difficulty conceiving and are at risk of diabetes and heart disease. Researchers from the Hospital for Sick Children in Toronto, Canada, conducted a large review of the medical literature, including eight studies of metformin taken during the first trimester of pregnancy by a total of nearly 500 women with either PCOS or diabetes. From the pooled data, the malformation rate in the treatment group was 2 percent compared with 7 percent in disease-matched control subjects who did not receive metformin. The researchers found that after the data were adjusted for publication bias, metformin had a statistically significant protective effect of 57 percent against major malformations in the fetus. The above findings are still preliminary and further studies are needed to confirm the safety of this drug in pregnancy. Other studies assessing the incidence of spontaneous abortion, stillbirth, minor abnormalities, intrauterine growth retardation and preterm labour still need to be conducted.