Polycystic ovary syndrome (PCOS) is a hormonal disorder that affects 5 to 10 percent of premenopausal women, and is the primary cause of ovulation problems in women of reproductive age. Women who have PCOS commonly have an irregular or absent period, high levels of testosterone, and often need help conceiving.
Typically, the first line of treatment for women with PCOS who have trouble ovulating is clomiphene (e.g., Clomid), a non-steroidal fertility medicine. However, in 2001, Robert Casper, MD, who did his fertility training at UC San Diego, published a report indicating that letrozole – a medicine used to treat breast cancer and not approved by the FDA in the treatment of fertility – helps women with PCOS ovulate. Since that initial report, several other clinical studies have suggested that letrozole, may be superior for stimulating ovulation.
Recently, a large-scale clinical trial funded by the National Institutes of Health (NIH) compared the rate of pregnancy in women who are treated with letrozole to those treated with clomiphene. These two medicines were randomly given to 750 infertile women diagnosed with PCOS; neither the patient nor their physician knew which of the two medicines was being prescribed.
While both groups had about a 30 percent miscarriage rate, the study found a higher occurrence of ovulations and pregnancies in the letrozole group than the clomiphene group. More importantly, women taking letrozole had an overall 44 percent increased chance of a live birth compared to those taking clomiphene.
What This Means For You
Based on the evidence from this clinical study, if you have PCOS, you are more likely to ovulate and have a live birth with letrozole than with clomiphene.
The fertility experts at UC San Diego Health are working on switching patients who are currently receiving clomiphene for ovulation difficulties to letrozole-based treatment.
The New England Journal of Medicine. July 10, 2014
Legro RS, et al. (USA)
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The New England Journal of Medicine.