Remember that the information presented here is not intended to replace the care of your own doctor. Before making any changes in the management of your own illness, you should consult your physician or other qualified medical professionals.
Question
I am on metformin for PCOS and am pregnant, but I do not have diabetes. My doctor said it was okay to remain on the drug and that he routinely advocates discontinuance at about 20 weeks gestation. However, your information on metformin states the following:Tell your doctor if you plan to become pregnant or have become pregnant. As with other oral glucose-control medications, you should not take GLUCOPHAGE during pregnancy.What can you tell me about the reason for discontinuing both from your perspective and that of my doctor?
Answer
The issue isn't the diagnosis of diabetes or PCOS, but of the safety of the medication during pregnancy. Metformin (like many other medications) has not been extensively studied during pregnancy in the rigorous fashion that the FDA requires for obtaining an "indication" that it's okay to use during that time. However, it has been used for many years in some parts of the world during pregnancy (see for instance Metformin therapy and diabetes in pregnancyI don't understand why your doctor would feel comfortable with you taking metformin during early pregnancy, when fetal organs are forming, then suggests discontinuing it after that period: ask him.
There is a recent review of the use of metformin entitled Metformin in Obstetric and Gynecologic Practice: A Review. in the Obstetrical and Gynecological Survey, vol 59, number 2, p118-127. The last part of the abstract states
There is a large volume of research supporting the use of metformin treatment in diabetes mellitus, androgenization, anovulation, infertility and recurrent miscarriage. Although metformin is known to cross the placenta, there is, as yet no evidence of teratogenicity. Metformin has an array of complex actions, accounting for the varied clinical roles, many of which are still to be fully evaluated. Much research is still needed.
My own experience has been from referrals of women with PCOS who have been managed by infertility specialists and are newly pregnant. Their doctor has recommended that they continue the use of metformin due to some evidence that it may reduce miscarriages and perhaps the development of gestational diabetes. I caution the patients that the studies supporting this are limited. However, many of these patients have struggled to achieve a pregnancy and are reluctant to stop therapy. Thus, I continue therapy with caution, but have yet to see a bad outcome.
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