A male contraceptive pill was found to be 99% percent effective at preventing pregnancy in mice, with no side effects, according to a press release published by the American Chemical Society on March 23.

The study was conducted by Md Abdullah Al Noman, a graduate student at the University of Minnesota, alongside a team of researchers. Over the course of four weeks, they administered the mice a daily dose of a molecule called YCT529, which resulted in plummeting sperm count. Four to six weeks after the treatment stopped, the mice started reproducing as usual.

“Scientists have been trying for decades to develop an effective male oral contraceptive,” Noman told The Hill. He added that there are currently no approved male birth control pills on the market. Not only that, the pill does not contain hormones. The use of hormones in birth control pills have been tied to side effects such as weight gain or depression. “We wanted to develop a non-hormonal male contraceptive to avoid these side effects,” said Noman.

Human trials will be conducted as soon as the third or fourth quarter of 2022, according to a press release. The team said they are exploring other compounds as it can be difficult to predict if an experiment on mice will have the same results during a human trial.

Although the research is being led by Noman, the University of Minnesota has been looking into making birth control pills for quite some time, as reported by Fortune. Other research centers are also developing new contraceptives geared towards men. A male contraceptive gel, which is rubbed on the shoulder daily, is currently in clinical trials at UC Davis Health. A birth control gel for women was approved in 2020. It was the first non-hormonal contraceptive to be developed in decades.

Photo Credit: Getty Images/Peter Dazeley