The study, in Phase 2b trials, included 222 men who completed at least three weeks of daily treatment with a gel made from the progestin medication segesterone acetate and testosterone. The compound was developed by the Population Council, a nonprofit organization that focuses on reproductive health, in collaboration with the National Institutes of Health.
In the trial, researchers conducted sperm count tests every four weeks to evaluate suppression of sperm. They aimed for a sperm count of 1 million or fewer per milliliter for effective contraception. Normal sperm count is between 15 million and 200 million sperm per milliliter of semen. By Week 15, 86 percent of participants achieved the low threshold, with sperm production typically suppressed by the eighth week of treatment.
Diana Blithe, chief of the Contraceptive Development Program at the National Institutes of Health, said the findings marked a milestone and said she considers male contraception as much a men’s health issue as a women’s.
Blithe said women who participated in the clinical trials with their partners felt relieved when they were able to stop using hormonal birth control for the study’s duration.
“There are a lot of women who have difficulties with various contraceptive methods, and one eye-opening aspect of the clinical trial has been listening to women and hearing what it meant to them to be in the study, especially when they were able to stop using their birth control for a year,” Blithe said.
The only effective forms of birth control on the market for men are vasectomies, which are not easily reversible, and condoms, which have a low acceptance rate.
Here’s what to know about the gel being studied and the state of research into male contraception.