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Is It Safe To Take Metformin During Pregnancy?

What is Metformin And How Does It Work?

Metformin is a commonly prescribed oral medication that is used in the treatment of type 2 diabetes.(1,2,3) It is also used for off-label treatment of polycystic ovary syndrome (PCOS). Type 2 diabetes is today one of the most widespread conditions in the world that causes an increase in blood sugar levels. Polycystic ovarian syndrome, on the other hand, is a condition that causes cysts to develop on the ovaries in women of reproductive age.(4,5,6)

Insulin is a hormone in your body that helps you control the levels of blood sugar. The main issue in people with type 2 diabetes is a condition known as insulin resistance. This means that the body is unable to use insulin properly.(7) Metformin is prescribed to help relieve insulin resistance in people with type 2 diabetes. Metformin helps the body use insulin properly and therefore keeps your blood sugar levels under control.

Metformin also does a similar thing in the treatment of polycystic ovarian syndrome. This is because polycystic ovarian syndrome is also associated with insulin resistance and is known to worsen problems that result from this health condition.(8)

Metformin is especially useful in the treatment of both polycystic ovarian syndrome and diabetes during pregnancy. If you have diabetes, you know that it is very important that you maintain a healthy levels blood sugar level when you are pregnant. Keeping your blood sugar under control reduces the risk of many diabetic complications, and also reduces the risk of congenital defects and other complications in your pregnancy. Metformin helps a person achieve both these goals.

In fact, in cases of polycystic ovarian syndrome, Metformin can make a huge difference even before you get pregnant. Women with polycystic ovarian syndrome often find it difficult to conceive and face fertility issues. The condition can cause irregular or missed periods, and also causes small cysts to grow on the ovaries. Sometimes, it can also increase the size of the ovaries. Polycystic ovarian syndrome may also prevent the process of ovulation from occurring every month, and if you do not ovulate, there will be no egg to fertilize, hence no pregnancy.

Doctors prescribe metformin to help improve the rate of ovulation and increase the chances of becoming pregnant. The benefits of Metformin can also continue after you become pregnant. It can help decrease the risk of developing type 2 diabetes because of blood sugar problems caused by polycystic ovarian syndrome. Metformin also helps you shed the extra weight gained due to this condition.(9,10)

However, what about using Metformin when you are pregnant? Is it safe to continue using the drug when you are pregnant? Read on to find out more.

Is It Safe To Take Metformin During Pregnancy?

Metformin is generally considered to be safe to take during pregnancy due to the many benefits the medication has for both polycystic ovarian syndrome and type 2 diabetes. This holds true regardless of which condition you are taking the drug for. Even though Metformin does cross the placental barrier, it has not been associated with an increased risk of complications in your pregnancy or congenital disabilities.

Is It Safe To Take Metformin During Pregnancy?

If you are already taking the medication before you got pregnant, your doctor is likely to tell you to continue taking the drug through the course of your pregnancy. However, at the same time, the first line of treatment for diabetes during pregnancy is usually insulin. Your doctor is likely to prescribe a medication keeping your personal medical history in mind and what they believe is the best option for both you and your baby’s health.(11)

It might even be that even if you were not already on Metformin before you got pregnant, your doctor might prescribe it for you during your pregnancy. For example, if you are already taking insulin for managing your type 2 diabetes, your doctor may consider prescribing Metformin along with insulin to get better control over your blood sugar levels.

In some cases, your doctor may prescribe Metformin if you are at a higher risk of developing gestational diabetes, which is a form of diabetes that develops during pregnancy, typically between the 24th and 28th weeks of pregnancy.(12)

Another review published in the Human Reproduction Update also noted that women who consumed Metformin for treating gestational diabetes gained less weight as compared to women who took insulin.(13) A two-year follow-up study found that babies born to women who had Metformin had lesser fat around their organs, which is a sign that they will be less prone to develop insulin resistance later in life. This also means that children who are exposed to Metformin in utero are more likely to experience long-term benefits. However, this is only a hypothesis currently, and there is a need for more long-term studies to ascertain anything.

One more factor to keep in mind with regards to the many benefits of Metformin during pregnancy is that certain studies have shown that women with polycystic ovarian syndrome who take this medicine during pregnancy have a lower risk of miscarriage.(14)

A review of studies carried out in 2014 and published in Human Reproduction Update discovered that Metformin did not cause congenital disabilities, pregnancy complications, or other diseases.(15)

Are There Any Risks And Side Effects Of Taking Metformin?

When consumed as per your doctor’s instructions, the side effects and risks of Metformin are very low. However, some people may experience some mild side effects. The most common side effects associated with Metformin include:

For pregnant women, such kinds of side effects from Metformin may make morning sickness worse. It is essential, therefore, that you are on the lowest effective dosage of Metformin during your pregnancy to help prevent or at least reduce the side effects of the drug.

Metformin is also known to lower the blood sugar levels too much, which can lead to hypoglycemia.(16)

Some of the common symptoms of hypoglycemia to watch out for include:

  • Persistent headache
  • Weakness and fatigue
  • Irritation
  • Confusion
  • Drowsiness
  • Dizziness
  • Hunger
  • Sweating or chills
  • Fast heart rate
  • Feeling jittery or shaking

There is a low risk of serious complications like lactic acidosis with Metformin. Lactic acidosis occurs when there is an excessive buildup of lactic acid in the tissues. Lactic acidosis is usually caused by problems with your metabolism.(17,18) Symptoms of lactic acidosis may include:

  • Nausea and vomiting
  • Irregular heart rate
  • Sharp abdominal pains or cramps
  • Dizziness
  • Feeling light-headed
  • Weakness
  • Muscle pains
  • Trouble breathing
  • Extreme fatigue or tiredness
  • Difficulty sleep or having less sleep

If you feel like you are experiencing any of the severe symptoms or signs of lactic acidosis and you are pregnant, you should immediately call your local emergency number or head to the nearest emergency room.

What is the Right Dosage of Metformin in Pregnancy?

For people with type 2 diabetes, the dosage of Metformin varies from person to person and depends on several factors, including their insulin sensitivity levels, sensitivity to side effects, their age, for how long they have had the condition and their overall medical history.

Pregnant women who are on insulin for the treatment of type 2 diabetes may also be prescribed Metformin to help with the symptoms of the condition that may develop during pregnancy. To minimize any side effects, doctors will start you off on very low doses of Metformin and then gradually increase the dose until the symptoms become manageable.

The dosage for women with polycystic ovarian syndrome also varies from person to person and depends on the reaction to the medication. If the side effects become unmanageable, your doctor is likely to bring you down to a lower dose or look for other treatment options.

When used correctly, Metformin is known to have a high safety profile.

What are the Alternatives to Metformin During Pregnancy?

Pregnant women who develop gestational diabetes or have type 2 diabetes are usually given Metformin during their pregnancy. However, if you develop an adverse reaction to the drug, or you experience certain changes to your gastrointestinal system, or even if you simply do not want to take Metformin, your doctor will look for other options.

The most common alternative to Metformin is treatment with insulin alone, which will help keep your blood sugar levels stable.

Recall of Metformin Extended Release

It is important to note that in May 2020, the Food and Drug Administration recommended that some of the manufacturers of Metformin extended release have to remove some of their medicine from the US market. This was done because it was found that there was an unacceptable level of a potential carcinogen (which is a cancer-causing agent) in some of the extended release Metformin tablets. If you are taking Metformin extended release tablets, it is important to find out from your doctor on whether you should continue taking the medication or if you need to have your prescription changed.


Metformin has a very low risk of causing any congenital disabilities and complications for the mother and baby. Nevertheless, there are still more clinical trials going on to find out more. Some studies have shown that Metformin may even provide several benefits for pregnant women and their babies if the drug is taken correctly. The dosage of Metformin needs to be managed and monitored by your doctor.

Metformin is also safe to take when you are breastfeeding your child. While trace amounts of the drug have been detected in breast milk, but it has not been found to harm or impact the child’s growth and development in any way.

If you have questions or you are worried about taking Metformin before or during your pregnancy, you should talk to your doctor, who can better explain the risks and benefits of using Metformin during pregnancy.

Also Read:


  1. Mather, K.J., Verma, S. and Anderson, T.J., 2001. Improved endothelial function with metformin in type 2 diabetes mellitus. Journal of the American College of Cardiology, 37(5), pp.1344-1350.
  2. Mather, K.J., Verma, S. and Anderson, T.J., 2001. Improved endothelial function with metformin in type 2 diabetes mellitus. Journal of the American College of Cardiology, 37(5), pp.1344-1350.
  3. Ferrannini, E., 2014. The target of metformin in type 2 diabetes. New England journal of medicine, 371(16), pp.1547-1548.
  4. Lord, J.M., Flight, I.H. and Norman, R.J., 2003. Metformin in polycystic ovary syndrome: systematic review and meta-analysis. Bmj, 327(7421), p.951.
  5. Mathur, R., Alexander, C.J., Yano, J., Trivax, B. and Azziz, R., 2008. Use of metformin in polycystic ovary syndrome. American journal of obstetrics and gynecology, 199(6), pp.596-609.
  6. Diamanti‐Kandarakis, E., Economou, F., Palimeri, S. and Christakou, C., 2010. Metformin in polycystic ovary syndrome. Annals of the New York Academy of Sciences, 1205(1), pp.192-198.
  7. Chakrabarti, R. and Rajagopalan, R., 2002. Diabetes and insulin resistance associated disorders: disease and the therapy. Current science, pp.1533-1538.
  8. Açbay, Ö. and Gündoğdu, S., 1996. Can metformin reduce insulin resistance in polycystic ovary syndrome?. Fertility and sterility, 65(5), pp.946-949.
  9. Velazquez, E.M., Mendoza, S., Hamer, T., Sosa, F. and Glueck, C.J., 1994. Metformin therapy in polycystic ovary syndrome reduces hyperinsulinemia, insulin resistance, hyperandrogenemia, and systolic blood pressure, while facilitating normal menses and pregnancy. Metabolism, 43(5), pp.647-654.
  10. Hundal, R.S. and Inzucchi, S.E., 2003. Metformin. Drugs, 63(18), pp.1879-1894.
  11. Priya, G. and Kalra, S., 2018. Metformin in the management of diabetes during pregnancy and lactation. Drugs in context, 7.
  12. Goh, J.E.L., Sadler, L. and Rowan, J., 2011. Metformin for gestational diabetes in routine clinical practice. Diabetic Medicine, 28(9), pp.1082-1087.
  13. Sivalingam, V.N., Myers, J., Nicholas, S., Balen, A.H. and Crosbie, E.J., 2014. Metformin in reproductive health, pregnancy and gynaecological cancer: established and emerging indications. Human reproduction update, 20(6), pp.853-868.
  14. Zeng, X.L., Zhang, Y.F., Tian, Q., Xue, Y. and An, R.F., 2016. Effects of metformin on pregnancy outcomes in women with polycystic ovary syndrome: a meta-analysis. Medicine, 95(36).
  15. Cassina, M., Dona, M., Di Gianantonio, E., Litta, P. and Clementi, M., 2014. First-trimester exposure to metformin and risk of birth defects: a systematic review and meta-analysis. Human reproduction update, 20(5), pp.656-669.
  16. Al-Abri, S.A., Hayashi, S., Thoren, K.L. and Olson, K.R., 2013. Metformin overdose-induced hypoglycemia in the absence of other antidiabetic drugs. Clinical Toxicology, 51(5), pp.444-447.
  17. Lalau, J.D., Lacroix, C., Compagnon, P., De Cagny, B., Rigaud, J.P., Bleichner, G., Chauveau, P., Dulbecco, P., Guérin, C., Haegy, J.M. and Loirat, P., 1995. Role of metformin accumulation in metformin-associated lactic acidosis. Diabetes care, 18(6), pp.779-784.
  18. DeFronzo, R., Fleming, G.A., Chen, K. and Bicsak, T.A., 2016. Metformin-associated lactic acidosis: Current perspectives on causes and risk. Metabolism, 65(2), pp.20-29.
Sheetal DeCaria, M.D.
Sheetal DeCaria, M.D.
Written, Edited or Reviewed By: Sheetal DeCaria, M.D. This article does not provide medical advice. See disclaimer
Last Modified On:June 16, 2021

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