Women Taking Clomiphene More Likely To Become Pregnant Than Women Taking Metformin, NEJM Study Says

Main Category: Women's Health / Gynecology
Also Included In: Fertility;  Pregnancy / Obstetrics
Article Date: 15 Feb 2007 - 9:00 PDT


Women who have polycystic ovary syndrome and take the drug clomiphene are more likely to become pregnant than women with PCOS who take the drug metformin, according to a study published in the Feb. 8 issue of the New England Journal of Medicine, the Washington Post reports (Washington Post, 2/13). PCOS is a hormonal imbalance that affects approximately 5% to 10% of U.S. women of reproductive age and is the most common cause of infertility in women. PCOS can cause a lack of ovulation, polycystic ovaries, irregular menstruation or missed periods, and clinical or biochemical evidence of high androgen levels -- such as facial hair or male pattern balding. Other symptoms include weight gain, insulin resistance and skin discoloration (Kaiser Daily Women's Health Policy Report, 8/31/05). For the study, which was funded by the National Institute for Child Health and Human Development, researchers from NIH and the University of Pennsylvania School of Medicine enrolled 626 infertile women with PCOS in three groups. The first group took only clomiphene, the second only metformin and the third a combination of the two drugs. Researchers tested the women's progesterone levels to determine when they were ovulating (University of Pennsylvania School of Medicine release, 2/7). The women were asked to have sexual intercourse every two to three days, and they took the drugs daily for up to six months and stopped if they became pregnant. Sixty percent of the women who took both drugs ovulated, compared with 49% for women who took only clomiphene and 29% for women who took only metformin, the study found (Washington Post, 2/13). The study also found that 26.8% of women in the combination group gave birth, 22.5% of women in the clomiphene-only group and 7.2% of the women in the metformin group. Obese women were less likely to conceive and were less likely to ovulate when taking metformin, according to the study. Christos Coutifaris, director of the Division of Reproductive Endocrinology and Infertility at the University of Pennsylvania and lead author of the study, said, "The bottom line here is that ovulation does not necessarily result in a successful pregnancy," adding, "The results suggest that an ovulation due to clomiphene is two times as likely to result in pregnancy compared to an ovulation caused by metformin" (University of Pennsylvania School of Medicine release, 2/7).

The study abstract is available online.

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