The contraceptive, which was created by researchers at the University of Minnesota, has been 99% effective at preventing pregnancy in mice, with no apparent side effects. Rather than using hormones, the pill targets interactions with vitamin A, which is a key component in fertility.

(Hormonal pills carry the potential of weight gain and changes in libido and could lower levels of “good” cholesterol, causing potential heart issues.)

The research team noted that mice who were given the compound, called GPHR-529, for four weeks showed a significant drop in semen, rendering them sterile. When the treatments were stopped, the mice returned to normal levels of virility within four to six weeks.

The research into this new birth control pill is being led by Md Abdullah Al Noman, a Ph.D. candidate at the school, who has been focusing on male contraception for several years. But the University of Minnesota has been looking into male birth control pills for quite some time.

In 2018, a pair of researchers said they had found a way to halt the movement of sperm by using an extract from a plant that African warriors and hunters once used as a heart-stopping poison on the tips of their arrows. Studies are still continuing on that contraceptive method.

A male contraceptive gel, which is rubbed on the shoulder daily, is also in clinical trials at present. (A gel-based birth control for women was approved in 2020.)