Finding out that you are pregnant while taking metformin can raise an important question: Is metformin safe during pregnancy?
The answer depends on why you take metformin and how your pregnancy is being managed. Current evidence has not found a clear increase in major birth defects from metformin use early in pregnancy. Still, metformin crosses the placenta, so doctors weigh its benefits and possible risks before deciding whether you should keep taking it.
If you take metformin and discover that you are pregnant, do not stop the medicine on your own. Talk with your doctor or pregnancy care team about what to do next.
Is Metformin Safe During Pregnancy?
Metformin may be used during pregnancy in some situations, but it is not the first-choice medicine for every pregnant person.
Current evidence is reassuring about early pregnancy exposure. Studies have not found an increased risk of major birth defects when metformin is used during the first trimester.
The decision to use metformin during pregnancy depends on the reason you take it.
For example, the treatment plan may be different if you take metformin for:
- Type 2 diabetes
- Gestational diabetes
- Polycystic ovary syndrome (PCOS)
- High blood sugar before pregnancy
Your doctor will look at your blood sugar, health history, and pregnancy needs before making a decision.
Can You Take Metformin in Early Pregnancy?
Metformin may be continued during early pregnancy in some cases.
The available evidence has not shown that first-trimester metformin use increases the risk of major birth defects. The 2026 American Diabetes Association guidance also notes that continuing metformin during early pregnancy can be considered safe from the standpoint of major birth defects.
That does not mean everyone should continue taking it.
The reason for treatment matters. Someone taking metformin for diabetes may have different needs from someone who used it to help with ovulation.
Does Metformin Cause Birth Defects?
Current research has not shown a clear increase in major birth defects from metformin use during pregnancy.
This is reassuring for people who took metformin before they knew they were pregnant.
If you took metformin during the first few weeks of pregnancy, do not assume that your baby has been harmed. Contact your doctor and explain when you took the medicine and why it was prescribed.
Your healthcare team can decide whether any change in treatment is needed.
Does Metformin Increase the Risk of Miscarriage?
Studies have not shown a clear increase in miscarriage from metformin use during early pregnancy.
There is another important issue to consider. High blood sugar during pregnancy can also cause health problems for both the mother and baby. This means stopping metformin without another treatment plan may not be a good choice for someone who needs help controlling blood sugar.
Your doctor can balance the need for good blood sugar control with the possible risks of medication exposure.
Does Metformin Cross the Placenta?
Yes. Metformin crosses the placenta and reaches the developing baby.
This is one reason doctors do not treat metformin as a completely risk-free medicine during pregnancy. Current ADA guidance notes that metformin can reach the fetus, with levels in umbilical cord blood sometimes similar to or higher than the mother’s blood levels.
Researchers continue to study what this exposure may mean for children later in life.
Some studies have found differences in childhood weight or growth after metformin exposure during pregnancy, while other studies have not found the same results. The findings are not fully consistent, so more research is still needed.
Is Metformin Safe for Gestational Diabetes?
Metformin may be used in some cases of gestational diabetes, but it is not the preferred first-line medicine in current ADA guidance.
The American Diabetes Association recommends insulin as the preferred medicine when medication is needed to manage diabetes during pregnancy. Metformin is not recommended as a first-line option because it crosses the placenta and may not provide enough blood sugar control for everyone.
Some people may still use metformin when insulin is not a safe, practical, or acceptable option after discussing the benefits and risks with their healthcare team.
Why Is Insulin Preferred During Pregnancy?
Insulin is the preferred medicine for managing high blood sugar during pregnancy because it does not cross the placenta in the same way metformin does.
Metformin does cross the placenta. That does not mean it is known to cause birth defects. It means the baby is exposed to the medicine, and doctors need to consider what is known and what is still uncertain about long-term effects.
Your doctor may recommend insulin if your blood sugar cannot be kept within the recommended range with diet and other measures.
Can You Take Metformin for PCOS During Pregnancy?
If you were taking metformin for PCOS, the answer may be different.
Some people use metformin to help with insulin resistance or to support ovulation before pregnancy. Once pregnancy occurs, there may not be a clear reason to keep using it for ovulation.
The 2026 ADA guidance says metformin used for PCOS and ovulation induction should be stopped by the end of the first trimester.
Your doctor may give you different advice if you have another reason to take metformin, such as diabetes.
What If You Find Out You Are Pregnant While Taking Metformin?
Do not panic.
If you have a positive pregnancy test while taking metformin, contact your doctor or pregnancy care team. Give them details about your treatment, including:
- Your current metformin dose
- The reason you take metformin
- When you started taking it
- Any other medicines you use
- Your recent blood sugar results, if available
Your doctor may continue metformin, change your treatment, or switch you to insulin.
The right choice depends on your situation.
Should You Stop Metformin When You Become Pregnant?
Do not stop metformin without medical advice.
This is especially important if you take metformin to control diabetes.
Stopping it suddenly may cause your blood sugar to rise. High blood sugar during pregnancy can increase the risk of problems for both you and your baby.
Your doctor may decide that you should continue metformin for a period of time or change to insulin. The decision should be based on your blood sugar and the reason you need treatment.
Can Metformin Prevent Gestational Diabetes?
Metformin is not a reliable way to prevent gestational diabetes.
Current ADA guidance reports that metformin did not reduce the risk of gestational diabetes in high-risk people with obesity, PCOS, or insulin resistance in a review of randomized trials.
If you have a higher risk of gestational diabetes, your doctor can recommend the right screening and prevention plan.
What Are the Possible Side Effects During Pregnancy?
Metformin can cause some of the same side effects during pregnancy as it does at other times.
Common problems include:
- Nausea
- Diarrhea
- Stomach pain
- Gas
- Reduced appetite
Pregnancy itself can also cause nausea and stomach changes, so it can sometimes be hard to know what is causing a symptom.
Tell your doctor if side effects become hard to manage. Your treatment may need to be adjusted.
When Should You Contact Your Doctor About Metformin?
Talk with your healthcare professional if:
- A pregnancy test comes back positive
- Pregnancy is being planned
- Blood sugar stays above the recommended pregnancy range
- Nausea, vomiting, or diarrhea becomes difficult to manage
- Kidney problems are present
- Other diabetes medicines are being used
- There is uncertainty about continuing metformin
Do not make medication changes based only on information you find online.
What If You Have Kidney Problems During Pregnancy?
Kidney health is important when taking metformin.
Your kidneys help remove metformin from your body. If kidney function becomes poor, metformin may build up in the body and become less safe.
Tell your doctor if you have kidney disease or have been told that your kidney tests are abnormal.
Your healthcare team can check your kidney function and decide whether metformin remains suitable.
Is Metformin Safe Throughout the Whole Pregnancy?
There is no simple yes-or-no answer.
Metformin has not been linked to an increased risk of major birth defects when used early in pregnancy, but it crosses the placenta and long-term effects on children are still being studied.
For diabetes during pregnancy, insulin is the preferred treatment in current ADA guidance. Metformin may be considered in selected situations after the benefits and possible risks have been discussed.
Your treatment may also change as pregnancy progresses because blood sugar needs can change during pregnancy.
What Should You Do If You Are Planning a Pregnancy?
If you take metformin and want to become pregnant, speak with your doctor before trying to conceive.
This gives your healthcare team time to:
- Check your blood sugar
- Review your medicines
- Check kidney function when needed
- Review your metformin treatment
- Set a pregnancy blood sugar goal
- Make a plan for your diabetes care
Good blood sugar control before and during pregnancy is important for your health and your baby’s development.
Is Metformin Safe During Pregnancy?
Metformin may be safe for some people during pregnancy, but it is not the right choice for everyone. Current evidence has not found an increased risk of major birth defects from metformin use in early pregnancy.
Metformin does cross the placenta, which is why doctors consider its benefits and possible long-term risks before continuing it. For diabetes during pregnancy, insulin is currently the preferred treatment according to the American Diabetes Association.
If you are pregnant or planning to become pregnant, speak with your doctor before starting, stopping, or changing metformin.
Related Diabetes Resources
- Metformin safety and precautions
- Comparing metformin with semaglutide for diabetes
- Glipizide and metformin combination treatment
Medical Disclaimer
This content is for general health education and does not replace advice from a qualified healthcare professional. Metformin use during pregnancy depends on the reason for treatment and your individual health needs. Speak with your doctor before changing or stopping metformin during pregnancy.