CU Expert’s Fertility Research on Unexplained Infertility Published in The New England Journal of Medicine

More than 100 Colorado women participated in the 4-year NIH clinical trials seeking to improve infertility treatment for women nationwide

DENVER (Sept. 30, 2015) – Highlighting an important discovery in treatment of women’s infertility, The New England Journal of Medicine published an article co-authored by Dr. Nanette Santoro, a physician with the University of Colorado OB-GYN about the benefits of the drug letrozole on women with unexplained infertility.

“We found that letrozole does significantly reduce multiple births, but the live birth rate is also considerably lower than with other medications,” said Santoro, who is Professor and Chair, Reproductive Endocrinology and Infertility in the CU Department of Obstetrics and Gynecology. “Clomiphene remains the first-line agent with best results although couples who use injectable medications need to be aware of the much higher risk of multiple pregnancies.”

Unexplained infertility is the diagnosis given when no specific cause was found after appropriate testing. An estimated 1-2 million women in the U.S. age 15-44 experience unexplained fertility and it accounts for anywhere from 15-30 percent of all infertility cases. The condition is frequently treated with drugs that stimulate hormones to improve a woman’s ovulation.

The Reproductive Medicine Network study sought to determine if using the drug letrozole to stimulate ovulation, instead of other drugs currently used as standard therapy, would result in fewer multiple gestations while maintaining similar live birth rates. Multiple gestation, which means pregnancy with twins or more, presents major health risks for mother and child, and infertility physicians want to reduce those risks. The Reproductive Medicine Network study came out of a four-year clinical trial sponsored by the National Institutes of Health called the Assessment of Multiple Intrauterine Gestations from Ovarian Stimulation (AMIGOS).

CU OB-GYN’s participation involved more than 100 Colorado women with unexplained infertility. Sarah Horrigan and her husband Chris participated in the trial at the former CU Advanced Reproductive Medicine. The couple had been trying to conceive for four years prior without success.

“Going through fertility treatment was not something I wanted to keep a secret. I’m not ashamed of it, and I encouraged people that I know who were struggling to reach out and get some help,” said Sarah. Within a month, Sarah conceived and gave birth to a son, Christopher Joel.

All trial participants had been trying to conceive without success and all had unexplained infertility – no problem with fallopian tubes, ovulation or egg reserve and no problem with their partner’s sperm. Santoro said that unexplained infertility can be very difficult emotionally: patients know they have a problem conceiving, but fertility doctors have done all their tests and still can’t determine what the problem is.

CU OB-GYN is one of seven institutions that took part in the NIH clinical trial. Involving 900 women nationwide, this is the first large-scale study to compare the oral medications clomiphene citrate, letrozole and the injectable hormone gonadotropin as treatments for unexplained infertility.

Fertility research results

Following treatment with gonadotropins, clomiphene citrate or letrozole, clinical pregnancies occurred in 35.5%, 28.3% and 22.4% of cycles, respectively. Live birth occurred in 32.2%, 23.3%, and 18.7% of cycles respectively. Pregnancy rates with letrozole were significantly lower than combined rates obtained with standard therapy of gonadotropin or clomiphene (p =0.003), or gonadotropin alone (p<0.001), but not clomiphene alone (p=0.10).

About University of Colorado OB-GYN

University of Colorado OB-GYN is one of the most diversified OB-GYN practices in the Denver area. Notable services at our women’s health clinics include university hospital care with a private practice model, women’s health research & studies, contraception, pregnancy care, infertility treatment, VBAC (vaginal birth after cesarean), & menopause treatment.