A vaginal ring used once a week to supplement the progesterone of women undergoing in vitro fertilization is as effective in getting them pregnant as a vaginal gel that must be applied every day, according to the results of the Phase III clinical trial for the Milprosa vaginal ring, Milprosa manufacturer Teva Pharmaceutical Industries announced Monday.

The study found that clinical pregnancy rates at eight and 12 weeks were comparable for both groups, with slightly fewer than half the women undergoing treatment getting pregnant at each point. Almost all the patients pregnant at week 12, when progesterone treatment ended, went on to have a live birth: 97.4 percent for the Milprosa group and 96.5 percent for the vaginal gel group.

“The study results demonstrate that Milprosa may be an effective and safe option for progesterone supplementation during the luteal phase (the latter part of the menstrual cycle) among women undergoing IVF,” said Dr. Laurel Stadtmauer, who authored the study and is a professor of obstetrics and gynecology at Jones Institute for Reproductive Medicine at Eastern Virginia Medical School. “Since normal luteal function may be compromised among women undergoing IVF, progesterone supplementation is essential and the more options patients have, the better. If approved, the once-weekly dosing of Milprosa may offer convenience for patients.”

Teva said the safety rates were also comparable between the Milprosa group and the group using gel with an 8-percent progesterone level. Serious adverse events – most commonly including nausea, headache, abdominal or back pain and fatigue – occurred in approximately 12 percent of patients in both treatment groups.

The Phase III data has been published in the scientific journal Fertility and Sterility.

The randomized, single-blind study was conducted at 22 clinical sites in the United States and included 1,297 patients between the ages of 18 and 42. Of enrolled patients, 646 were randomized to Milprosa and 651 to the vaginal gel.