Metformin 'safe in pregnancy', says MHRA

Prescribing advice for metformin in pregnancy has been updated after a large study showed no safety concerns in this setting.

A pregnant woman is seen from above as she sits cross-legged on a bed taking a pill with a glass of water.
Metformin can be used during pregnancy and the periconceptional phase as an addition or an alternative to insulin, if clinically needed. | GETTY IMAGES

A non-interventional cohort study of population registries in Finland (the CLUE study) investigated both immediate and longer-term effects of exposure to metformin in utero on children born to patients with pre-existing type II diabetes, gestational diabetes, or polycystic ovary syndrome.

The results of the study were 'reassuring', said the MHRA, with no safety signals of concern identified for use of metformin in pregnancy relating either to those who were pregnant or their baby.

With regard to secondary outcomes, similar rates of births that were small for gestational age were observed with exposure to metformin and within the group of patients with untreated gestational diabetes. An increased risk of small for gestational age was observed with exposure to metformin compared with insulin, which may relate to an overall increase in body weight due to use of insulin.

In light of the findings, the licence for Glucophage has now been updated to reflect that the drug can be considered for use during pregnancy and the periconceptional phase as an addition or an alternative to insulin, if clinically needed. This is consistent with current clinical guidance.

The licences for other metformin products are also being updated. The product information for fixed-dose combination products containing metformin will be reviewed and updated if appropriate.

Untreated diabetes

Uncontrolled hyperglycaemia in the periconceptional phase and during pregnancy is associated with increased risks to the baby and the patient. Good blood glucose control reduces the risk of congenital abnormalities, pregnancy loss, pregnancy-induced hypertension, preeclampsia, and perinatal mortality.

NICE and SIGN guidelines already recommend metformin for use in diabetes during pregnancy and gestational diabetes if a healthcare professional feels it is appropriate.

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