Metformin reduces blood sugar levels and is approved by the FDA for treatment of type 2 diabetes. In women with infertility due to polycystic ovarian syndrome (PCOS), trials found metformin plus Clomid to be more effective than Clomid alone in ovulation induction. Continued metformin treatment may establish regular menstrual cycles in women with PCOS. 

Metformin may also decrease the miscarriage risk associated with PCOS. These findings are preliminary, based on two small studies. One small study found metformin might also decrease the incidence of gestational diabetes in PCOS women. The safety of metformin's use in pregnancy has not been established. 

For most women with PCOS trying to conceive, the first medication option to induce ovulation is still Clomid. However, metformin is arguably the first choice in women with impaired glucose tolerance and certainly in women with type 2 diabetes. 

How Metformin Works

Metformin has many actions, the main being suppression of endogenous glucose production by the liver. Metformin does not cause hypoglycemia, weight gain, unfavorable alteration of lipids, nor increase insulin secretion. 

Unlike drugs such as Avandia, metformin does not cause weight gain, fluid retention, or potential idiosyncratic hepatotoxicity. Instead, metformin improves the effectiveness of insulin while maintaining or even decreasing insulin levels. Metformin decreases both basal and postprandial glucose levels, without the danger of hypoglycemia. Glucophage promotes weight loss and favorable changes in the lipid profile.

Possible Metformin Side Effects

Metformin is a very safe medication when used properly and given to healthy women. It is contraindicated in women with renal compromise, liver disease, and at risk for lactic acidosis. Gastrointestinal side effects such as diarrhea or nausea are initially very common, but usually subside. Taking Glucophage with food and slowly building up to the target dosage of 1,500 to 2,000 mg total per day can mitigate these effects.

Women with liver dysfunction, excessive alcohol intake, or severe illness should not take metformin.