Healthy pregnancy hub

Metformin (Glucophage®)

Last Update: 09 Apr 2025

Welcome to our fact sheet on metformin (Glucophage®) during pregnancy and breastfeeding/ chestfeeding. This information is based on available published literature. This information should not take the place of medical care and advice from your healthcare provider.

The HEALTHY PREGNANCY HUB team is collaborating with MotherToBaby to share information on this topic. The original version is available here (updated from January 2024). 

Serene, our chatbot, can also answer your questions about medications during pregnancy. 

Please note that this fact sheet is based on United States information and has been adapted for Canada, with a review by our Canadian experts. Minor differences may exist between the two countries. Always consult your healthcare professional for information tailored to your situation. 

1. What is metformin?

Metformin is a medication that has been used to treat type 2 diabetes, insulin-resistance in polycystic ovary syndrome (PCOS), obesity (high body mass index (BMI)), and gestational diabetes. It is sold under brand names including Glucophage®, Glumetza® and Fortamet®. 

Sometimes when people find out they are pregnant, they think about changing how they take their medication, or stopping their medication altogether. However, it is important to talk with your healthcare providers before making any changes to how you take this medication. Your healthcare providers can talk with you about the benefits of treating your condition and the risks of untreated illness during pregnancy. 

High blood sugar levels before and during pregnancy increase the chance of birth defects and other complications. For more information about diabetes during pregnancy, please see the MotherToBaby fact sheets on Type 1 and Type 2 Diabetes here  and Gestational Diabetes here

2. What are the risks according to research?

I take metformin. Can it make it harder for me to get pregnant?

Based on the studies reviewed, it is not known if metformin can make it harder to get pregnant. Metformin has been used to treat PCOS, a condition that can make it harder to get pregnant. 

Does taking metformin increase the chance of miscarriage?

Miscarriage is common and can occur in any pregnancy for many different reasons. Metformin is not expected to increase the chance for miscarriage. Poorly controlled diabetes in the first trimester of pregnancy can increase the chance of miscarriage. 

Does taking metformin increase the chance of birth defects? 

Every pregnancy starts out with a 3-5% chance of having a birth defect. This is called the background risk. Use of metformin during pregnancy is not expected to increase the chance of having a baby with a birth defect. Poorly controlled diabetes in the first trimester of pregnancy can increase the chance of having a baby with a birth defect. 

Does taking metformin in pregnancy increase the chance of other pregnancy-related problems?

Some studies have suggested individuals with gestational or type II diabetes who were treated with metformin had smaller babies at the time of delivery than those who were treated with insulin. The children exposed to metformin during pregnancy quickly gained weight after birth. Some studies have shown that children exposed to metformin during pregnancy may have a higher chance of having obesity in childhood. However, other studies did not show a difference in obesity in children of individuals who took metformin in pregnancy compared to individuals who did not take metformin or those who took insulin. 

Does taking metformin in pregnancy affect future behavior or learning for the child?

Taking metformin during pregnancy is not expected to affect future behavior or learning for the child. 

3. Breastfeeding/ chestfeeding while taking metformin

Metformin gets into breastmilk/ human milk in small amounts. One study found no problems in breastfed/ chestfed infants. Be sure to talk to your healthcare provider about all of your breastfeeding/ chestfeeding questions. 

4. Fathers and sperm donors

If a male takes metformin, could it affect fertility or increase the chance of birth defects?*

It is not known if metformin could affect fertility (ability to get a partner pregnant) or increase the chance of birth defects above the background risk. Some studies have suggested that use of metformin may reduce testosterone levels while other studies have suggested that better control of insulin may help improve sperm production. One study suggested that fathers and sperm donors given a prescription for metformin in the 3 months before conception might be associated with genital defects in the infant. However, no higher chance for birth defects was reported in a different study that looked at ~1,700 children of fathers and sperm donors who were prescribed metformin to treat type 2 diabetes in the 3 months before conception. Prescription based studies cannot tell us if the person actually took the medication or if they took it correctly. In general, exposures that fathers and sperm donors have are unlikely to increase the risks to a pregnancy. For more information, please see the MotherToBaby fact sheet Paternal Exposures here.  

Key points

  • Metformin (Glucophage®) is a medication used to treat type 2 diabetes, gestational diabetes, and insulin resistance in polycystic ovary syndrome (PCOS).
  • Metformin is not expected to increase the risk of miscarriage or birth defects. It is not known whether metformin may affect fertility or cause other problems during pregnancy, nor what impact it may have if taken by the father or sperm donor.
  • Metformin passes into breast milk/ human milk in small amounts, but it does not seem to cause any harms for the nursing babies.
  • Always consult your healthcare provider before changing or stopping your treatment during pregnancy.

References

Please click here for references. 

*Section updated June 2024 

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Disclaimer

HEALTHY PREGNANCY HUB provides a source of information validated by health professionals; however, this information is provided for informational purposes only and should not replace professional advice. Medical standards and practices evolve as new data becomes available, so it is imperative to consult your doctor or a qualified health professional for any questions or concerns regarding your health without delay or omission. It is the responsibility of your treating physician or any other health professional, based on their independent experience and knowledge of the patient, to determine the best way to evaluate and treat you.

HEALTHY PREGNANCY HUB does not specifically recommend or endorse any test, practitioner, treatment, product, or opinion mentioned on our platform. HEALTHY PREGNANCY HUB also does not replace the individual patient assessment based on the examination by the healthcare provider of each patient and the consideration of laboratory data and other patient-specific factors.

The use of the information available on our site is at your own risk. No person involved in the creation, production, promotion, or marketing of HEALTHY PREGNANCY HUB guarantees or represents, expressly or implicitly, anything regarding the information available on the platform, which is provided “as it is”. All warranties are expressly excluded and disclaimed, including but not limited to implied warranties of merchantability or fitness for a particular purpose, as well as any warranties arising by law or otherwise in law or from trade or usage. Any statements or representations made by any other person or entity are void.

While consulting symptoms or other medical information on our platform may guide your discussions with your healthcare professional, this information should not be used to make a medical diagnosis or determine treatment. Before making changes to your supplement or medication regimen, please discuss with your medical team or contact 811 (Canada) to ensure the relevance of these changes to your individual situation.

Credits
MotherToBaby
Organization of Teratology Information Specialists (OTIS)
View source
Émy Roberge
Centre hospitalier universitaire Sainte-Justine

Associated Fact Sheets

Would you like to know more about this topic? Explore our associated Fact Sheets !

Associated Resources

Would you like to know more about diabetes? Explore our resources associated with this topic!

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