A hormonal contraceptive gel that can be applied daily to men’s shoulder blades is in clinical trials. Use of the male birth control led to a large reduction in sperm count, according to new research. (Getty Images)

There are countless forms of female birth control on the market. The latest version — a progestin-only daily pill — is available over the counter at drug stores across the nation.

But birth control for men is limited. Condoms are just 87% effective at preventing pregnancy, and vasectomies are categorized as permanent sterilization.

While some state and national efforts to secure access to contraception have stalled, a potential type of male birth control just experienced a major breakthrough during clinical trials.

A hormonal gel applied daily to the shoulder blades led to a significant decline in sperm production after nearly four months, according to findings presented at the Endocrine Society’s annual meeting last week. The ongoing trial started in 2018 and is backed by the National Institutes of Health.

Called NES/T, the gel contains segesterone acetate, a progestin medication that’s also used in vaginal rings, and testosterone, according to the society’s press release. The treatment lowers natural testosterone production in the testes but replaces it to maintain a sex drive.

Nearly 90% of the 222 men in the study saw a sperm count of 1 million — the threshold for effective male birth control — or less by week 15 of the daily gel use. While the second phase of the trial is complete, researchers will continue to look at the safety, efficacy and reversibility of the contraception, among other variables.

The latest news on the non-invasive method comes as scientists are also developing a male birth control pill and an injectable gel.

A study published in the journal Science last month examined the potential of a contraceptive pill for men by testing on mice. Baylor College of Medicine researchers focused on how to block serine/threonine kinase 33, or STK33, a protein found in the testes that is required for male fertility. A compound called CDD-2807 was the most effective at blocking STK33 in mice, but they regained their fertility after they stopped using it.

Meanwhile, a non-hormonal vasalgel called Plan A is also in the works, according to my colleague Kelcie Moseley-Morris. She spoke to developers of the gel in April 2023, who said the treatment could be injected into the vas deferens to block sperm. Plan A could last for 10 years, according to its backers, but it’s in early stages of development.

Whichever male birth control hits the market first, it’s clear access to contraception is a concern for the American public right now, two years since the U.S. Supreme Court overturned Roe v. Wade. For instance, 1 in 5 Americans believe the right to birth control is at risk, according to a March 2024 KFF poll.

“After Roe fell, women looked around and said, ‘What can you do?’ and men looked around and said, ‘Crap, what can I do?’” Heather Vahdat, the Male Contraceptive Initiative’s executive director, told States Newsroom last year. “Men are waiting for this; I think it’s really underestimated how much attention men are paying to this.”