Metformin

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Date: March 2026, Version 4.0

Quick read

Metformin can be used in pregnancy to treat diabetes.

What is it?

Metformin is mainly used to treat type 2 diabetes and gestational diabetes.

Benefits

What are the benefits of using metformin in pregnancy?

Metformin helps to keep blood sugar levels within a healthy range in people with diabetes. Good blood sugar control is important because it reduces long-term damage to your blood vessels, nerves, and eyes.

Poorly controlled type 2 diabetes in pregnancy increases the chance of miscarriage, birth defects in the baby, and stillbirth. Poorly controlled type 2 and gestational diabetes is linked to having a bigger baby, delivery complications, and problems with the baby’s blood sugar levels after birth. Using metformin can reduce these risks by keeping your blood sugar levels stable.

Risks

What are the risks of using metformin during pregnancy?

There are no known risks to your baby from using metformin in pregnancy.

Alternatives

Are there any alternatives to using metformin in pregnancy?

Possibly — either metformin or insulin can be used for treatment of diabetes in pregnancy. Some women may need to use insulin alongside metformin to ensure good blood sugar control.

No treatment

What if I prefer not to use metformin in pregnancy?

It is very important to keep your blood sugar well-controlled in pregnancy to protect your health and to prevent pregnancy complications. If your doctor has prescribed a medicine to treat diabetes, it is important to take it as recommended.

Are there any risks to my baby if the father uses metformin? 

Overall, the available information does not show that metformin used by the father around the time of conception affects the baby.

Will I or my baby need extra monitoring during pregnancy or after delivery?

As part of routine antenatal care in the UK, you will be offered a very detailed scan to check your baby’s development. This usually takes place at around 20 weeks of pregnancy. If you had diabetes with poor blood sugar control in the first trimester, you may be offered this scan from around 16 weeks of pregnancy.

If you have type 2 or gestational diabetes, you are more likely to have a larger than average baby. Extra monitoring of your baby’s growth will therefore be offered.

Metformin use around the time of delivery can lead to your baby having low blood sugar for a short period after birth. Your newborn baby’s blood sugar will be checked, and treatment will be given if necessary.

Who can I talk to if I have questions?

If you have any questions regarding the information in this leaflet, please discuss them with your health care provider. They can access more detailed medical and scientific information from www.uktis.org.

How can I help to improve drug safety information for pregnant women in the future?

Our online reporting system (MyBump Portal) allows women who are currently pregnant to create a secure record of their pregnancy, collected through a series of questionnaires. You will be asked to enter information about your health, whether or not you take any medicines, your pregnancy outcome and your child's development. You can update your details at any time during pregnancy or afterwards. This information will help us better understand how medicines affect the health of pregnant women and their babies. Please visit the MyBump Portal to register.

General information
Sadly, miscarriage and birth defects can occur in any pregnancy.

Miscarriage occurs in about 1 in every 5 pregnancies, and 1 in every 40 babies are born with a birth defect. This is called the ‘background risk’ and happens whether medication is taken or not.

Most medicines cross the placenta and reach the baby. For many medications this is not a problem. However, some medicines can affect a baby’s growth and development.

If you take regular medication and are planning to conceive, you should discuss whether your medicine is safe to continue with your doctor/health care team before becoming pregnant. If you have an unplanned pregnancy while taking a medicine, you should tell your doctor as soon as possible.

If a new medicine is suggested for you during pregnancy, please make sure that the person prescribing it knows that you are pregnant. If you have any concerns about a medicine, you can check with your doctor, midwife or pharmacist.

Our Bumps information leaflets provide information about the effects of medicines in pregnancy so that you can decide, together with your healthcare provider, what is best for you and your baby.