Male Birth Control Explained As New Pill 99 Percent Effective in Mice

A team of scientists has made headlines after stating that an in-development male birth control compound has been 99 percent effective in animal tests.

The male contraceptive, which can be taken orally, targets a protein in the body called the retinoic acid receptor alpha, or RAR-α, which plays a part in cell growth and sperm formation.

Researchers examined this protein and designed chemical compounds that would effectively shut it off in cells. They found that one compound in particular, called YCT529, was effective at doing so.

When given to male mice for four weeks, it reduced sperm counts and was 99 percent effective in preventing pregnancy without any observable side effects, according to a press release from the American Chemical Society (ACS). The mice were able to father babies again within four to six weeks after they stopped taking the chemical.

Their findings were outlined at the ACS Spring 2022 meeting held from March 20th to the 24th.

According to Gunda Georg, head of the Department of Medicinal Chemistry at the University of Minnesota, who was involved in the work, human clinical trials are set to begin in the third or fourth quarter of this year.

The search for a male birth control pill has been going on for decades but none have been made available yet. At the moment, the two contraceptive methods available to men are condoms and vasectomy—the latter being a surgical procedure.

A number of other methods are being investigated. One type of hormonal male birth control pill, 11-beta-methyl-19-nortestosterone dodecylcarbonate, works by reducing levels of hormones required for sperm production.

A Phase I trial of the pill, led by researchers at the University of Washington School of Medicine along with UCLA a few years ago, found that subjects given the pill experienced drops in levels of two hormones associated with sperm production with mild side effects reported including fatigue, acne and headache, according to Clinical Trials Arena. The effects were reversible after stopping treatment.

Another type of pill called DMA undecanoate, which also works by suppressing male hormones to decrease production of sperm, is also under investigation.

Hormonal pills are a popular contraceptive method among women but they can come with side effects including weight gain, headaches, sore breasts, irregular periods, mood changes and decreased sexual desire, according to the American Academy of Family Physicians.

There are other potential methods for men that do not involve pills. ADAM is a birth control method being investigated by medical device company Contraline. It would work by injecting a gel into the vas deferens—a tube that transports sperm to the penis in preparation for ejaculation.

The gel is designed to block sperm from traveling through this tube. Eventually the gel liquifies and the barrier to sperm flow is removed.

Man holding condom and pills
A stock photo shows a man holding a condom in one hand and some pills in the other. Birth control pills for men are still being investigated after years of research. TanyaJoy/Getty