SUMMARY: Metformin is an antihyperglycaemic biguanide used in the management of type 2 diabetes. It acts by lowering the basal and postprandial plasma glucose without stimulating insulin secretion thereby reducing the risk of hypoglycaemia associated with insulin therapy. Metformin is also used off-label for the treatment of infertility secondary to polycystic ovarian syndrome (PCOS). 

The available data does not show an increased risk of congenital malformations or other adverse pregnancy outcomes. Where clinically indicated, use of metformin at any stage of pregnancy may be considered. 

Inadvertent exposure to metformin at any stage of pregnancy would not usually be regarded as medical grounds for termination of pregnancy or any additional fetal monitoring. 

Please report ALL cases of drug and/or chemical exposure in pregnancy to UKTIS by telephoning the service on 0844 892 0909 or by printing and completing a pregnancy reporting form, providing as many patient identifiers as possible to enable follow up of pregnancy outcome. This vital information enables UKTIS to provide evidence-based advice for future enquiries and to conduct surveillance of potential and known teratogens. 

For case specific advice please contact UKTIS on 0844 892 0909.