NIh: Clomiphene shows better results than letrozole for unexplained infertility

Treatment with clomiphene, a standard therapy for couples with unexplained infertility, results in more live births than treatment with a potential alternative, letrozole.

This was found in a study of more than 900 couples conducted by a National Institutes of Health research network.

The study authors undertook the comparison because earlier findings had suggested that letrozole might achieve as many live births as other treatments, but result in fewer multiple pregnancies. Moreover, a 2014 study by the same network found that letrozole was more effective than clomiphene for achieving pregnancy in women with another infertility disorder, polycystic ovary syndrome. The study appears in the New England Journal of Medicine.

Study author Esther Eisenberg, M.D., Fertility and Infertility Branch of the NIH’s Eunice Kennedy Shriver National Institute of Child Health and Human Development (NICHD), which supports the research network, said:

“Letrozole treatment offered no advantages over clomiphene treatment,”  “Women in the letrozole treatment group had fewer live births, but four times as many multiple pregnancies as women in the clomiphene group.”

The study’s first author was Michael P. Diamond, M.D. of the Department of Obstetrics and Gynecology, Georgia Regents University in Augusta.