Many women, especially those with unexplained infertility, are commonly treated with ovarian stimulation medications such as letrozole, gonadotropins or clomiphene citrate. The challenge has been to determine which medication is best at achieving and maintaining pregnancy while reducing multiple gestations. New research released by the Women & Infants Hospital of Rhode Island and The Warren Alpert Medical School of Brown University has revealed that one of these medications may work better than the others.
The study, published in the New England Journal of Medicine, involved a multicenter randomized trial of couples with unexplained infertility—those who have not been diagnosed with a particular problem that was causing their infertility. Women age 18 to 40 who were ovulating and had at least one Fallopian tube were randomized to up to four cycles of ovarian stimulation with gonadotropins, clomiphene citrate or letrozole. The researchers were looking at the frequency of multiple gestations among women with clinical pregnancies.
The research team concluded that standard treatment with clomiphene is better. They wrote: “In women with unexplained infertility, ovarian stimulation with letrozole resulted in significantly lower frequency of multiple gestations, but also a lower frequency of live births, as compared with gonadotropins, but not as compared with clomiphene.”
Ovarian stimulation medication promotes pregnancy by increasing the number of eggs that a woman produces and by enhancing implantation. “Unfortunately, ovarian stimulation can be complicated by ovarian hyperstimulation syndrome, which results in multiple gestations with increased risk of preterm birth,” explained Dr. Ruben Alvero, who co-led the study. “We designed this trial to assess whether ovarian stimulation with letrozole, as compared with clomiphene or gonadotropins, would result in lower rate of multiple gestations without lowering the likelihood of pregnancy. What we found is that clomiphene citrate should be used as the first-line agent for patients with unexplained infertility,” he said.
Be sure to discuss this study with your doctors.