What Is Metformin and Does It Help With Fertility?

Dealing with fertility issues can be heartbreaking and frustrating. If you are looking for ways to manage infertility, you may have come across a medication called metformin, which is sometimes used to help people get pregnant. While metformin is an effective drug for certain situations, it may not be for everyone dealing with a fertility issue.

We reached out to fertility experts to help us understand what metformin is, how it can help with fertility, who is a good candidate for it, and what questions to ask a healthcare provider if you are interested in learning more.

What Is Metformin?

Metformin is an oral medication commonly used to treat diabetes, explains Alex Robles, M.D., an OB/GYN and reproductive endocrinologist at Columbia University Fertility Center. "It works by decreasing glucose production in the liver and increasing insulin sensitivity," he says. "In combination with other medications, metformin can also help women with polycistic ovarian syndrome (PCOS), particularly if they have signs of insulin resistance."

According to the Centers for Disease Control and Prevention (CDC), insulin resistance is a condition where the cells in your body don't respond well to insulin, which can cause unhealthy amounts of glucose to build up. This can eventually lead to diabetes. Some people who have PCOS deal with fertility issues along with insulin resistance.

How might you know if you have insulin resistance? "Many people do not have diabetes or pre-diabetes by standard screening, but they can still develop insulin resistance," says Suzanne Bovone, OB/GYN at Obstetrics and Gynecology of San Jose, part of Pediatrix Medical Group. "A fasting blood glucose and insulin level can be taken to determine this."

Does Metformin Help With Fertility?

Metformin isn't usually prescribed for infertility issues alone, says Dr. Robles. "Metformin by itself is not a fertility medication," he explains. "However, it can be used in combination with other medications to help treat PCOS patients that do not get periods regularly and are not ovulating." If you are responding well to metformin, Dr. Bovone says that your physician may also recommend complementary medications, such as clomid or letrozole, to improve ovulation.

PCOS affects between 6 to 12% of people assigned female at birth. Besides irregular periods and ovulation problems, it can cause elevated levels of male hormones, resulting in excess facial and body hair and acne. PCOS also can lead to the development of small ovarian cysts.

Who Is Metformin Good For?

Metformin is approved by the FDA specifically for use in people with type 2 diabetes and insulin resistance, and is meant to be used along with diet and exercise to decrease blood sugar and enhance how the body responds to insulin.

When used in pregnancy, it should only be taken in certain situations, says Dr. Robles. "I only recommend metformin in people struggling to conceive who have PCOS and signs of insulin resistance," he shares.

Dr. Bovone agrees with this recommendation. "By decreasing glucose levels and improving insulin's effect on cell metabolism, reproductive hormones can signal each other better to allow ovulation to resume," she explains. "Metformin is not helpful for fertility for those who do not have PCOS and insulin resistance."

Risks and Metformin Side Effects

The most common side effects of metformin are gastrointestinal, and include bloating, nausea, diarrhea, and stomach aches. "Side effects can be limited by starting on a low dose and increasing over time," Dr. Bovone recommends. She also explains that there are several different formulations of metformin, including tablets or liquids. The liquid variation is usually better tolerated.

In rare circumstances, metformin can have serious side effects. "The most serious reaction is lactic acidosis; hence, metformin should not be used in renal insufficiency, heart failure, or severe systemic infection (sepsis)," Dr. Bovone advises. A 2022 review published in the Journal of Assisted Reproduction and Genetics found that taking metformin for fertility isn't likely to negatively impact fetal development, but any long term effects on infants is unknown at this time.

Questions to Ask Your Healthcare Provider

Whether or not you find a healthcare provider who will prescribe metformin for your fertility issues will depend on several factors, including your overall medical history. But first, it needs to be clear that you meet the criteria for taking metformin for fertility.

If you are interested in taking metformin, you should confirm with a physician that you indeed have PCOS and insulin resistance, says Dr. Bovone. "If all other tests are normal and it seems that PCOS with insulin resistance is present, then I will prescribe metformin," she says. She usually starts her patients on a low dose and increases gradually to lessen side effects. "Over a few months, we see if there is weight loss and improvement in ovulation."

Dr. Robles recommends discussing the pros and cons of the medication with a fertility doctor, as well as the potential for side effects that could occur at higher doses. The bottom line is that metformin can be a helpful medication for people with PCOS and insulin resistance, but even in those cases, it's not for everyone. That's why having an open and honest dialogue with a medical professional is key when you are deciding whether metformin is the best fertility medication for you.