Letrozole for Treating Infertility in Women with PCOS

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New research is showing that the breast cancer drug known as letrozole (Femara) may be a better option than Clomid to improve pregnancy rates in women with PCOS. This is great news for the millions of women who suffer from PCOS, the leading cause of ovulatory infertility in the United States.

Dr. Richard Legro, a reproductive endocrinologist at Penn State Hershey Medical Center presented results from his recent NIH-sponsored trial at the 2012 American Association of Reproductive Medicine (ASRM) conference that showed 25% percent of women treated with letrozole had a live birth compared to 16.8% of women who took cloned.

Traditionally, Clomid has been the first-line drug of choice to stimulate ovulation in women with PCOS but has a higher rate of multiple pregnancies and increases exposure to estrogen. In comparison, letrozole doesn't raise estrogen-like Clomid, has a lower risk of cardiac abnormalities and has a lower multiple pregnancy rate.

What Is Letrozole?

Letrozole is an aromatase inhibitor which prevents the conversion of androgen to estrogen. It also improves endometrial thickness and encourages healthy ovarian follicular development. While not approved by the FDA for this use, it has been shown to induce ovulation in women who do not ovulate. For this reason, some infertility specialists are using the drug in women who cannot tolerate or who do not respond well to Clomid.

Letrozole is a drug that is commonly used to treat estrogen-dependent tumors, particularly breast cancer in older, post-menopausal women.

Dosing:

Letrozole comes in 2.5mg tablets and is taken once a day for 5 days, usually beginning on day three or day five of your menstrual cycle. You may need monitoring through blood tests and/or ultrasounds to determine when you are approaching ovulation.

Side Effects:

Overall, letrozole is well tolerated.

Side effects may include:

Risks of Birth Defects:

It is important to note that this medication is incompatible with pregnancy and breastfeeding. However, please understand that you are taking this drug before you become pregnant, so it does not increase your risk for having a child with birth defects. Letrozole should be stopped as soon as pregnancy is achieved.

Edited by PCOS Expert Angela Grassi, MS, RDN

Sources:

Legro RS, Kunselman AR, Brzyski RG, Casson PR, Diamond MP, Schlaff WD, Christman GM, Coutifaris C, Taylor HS, Eisenberg E, Santoro N, Zhang H. The Pregnancy in Polycystic Ovary Syndrome II (PPCOS II) trial: rationale and design of a double-blind randomized trial of clomiphene citrate and letrozole for the treatment of infertility in women with polycystic ovary syndrome. Contemp Clin Trials. 2012 May;33(3):470-81.

Nayereh Ghomian, M.D., Ashraf Khosravi, M.D., and Nezhat Mousavifar, M.D. A Randomized Clinical Trial on Comparing The Cycle Characteristics of Two Different Initiation Days of Letrozole Treatment in Clomiphene Citrate Resistant PCOS Patients in IUI Cycles.

Int J Fertil Steril. 2015 Apr-Jun; 9(1): 17–26.

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