Why are there so few male birth-control options?

Red condom in a wrapper
Why so few male birth-control options? One of the biggest challenges is stopping the sheer volume of sperm produced each day. (Getty Images) (Getty Images/iStockphoto)

The promise of a male birth-control pill has been a dangling carrot for years. Potential new male contraceptives make headlines, but then never come to market. “The joke in the field is that the male contraceptive has been five years away for the last 40 years,” Dr. John Amory, a research physician at the University of Washington School of Medicine who specializes in novel forms of male contraception, told Bloomberg.

Men currently have only two primary contraceptives — the same ones they’ve had for decades: condoms and vasectomy. Condoms have been used since at least 3,000 B.C., though they weren’t produced at a large scale until 1860, followed by the revolutionary latex condoms in the 1920s. The first vasectomy, meanwhile, dates back to the 1820s, but it didn’t become popularized as a birth control method until around World War II.

Condoms, when used in real life rather than perfectly, are 85% effective at preventing pregnancy and are the only birth control method that reduces the risk of sexually transmitted infections, according to Planned Parenthood. Vasectomy — which has seen a spike in interest since Roe v Wade was overturned in June 2022 — is a surgery that cuts the vas deferens, tubes that carry sperm from the testicles to the urethra, according to the U.S. National Library of Medicine. A vasectomy is more than 99.99% effective in preventing pregnancies, making it one of the most effective forms of birth control, according to the Cleveland Clinic.

But condoms can fail and vasectomy is typically permanent. So for years the focus has been finding a medium-term, reversible contraceptive solution. But it hasn’t been easy.

New potential methods typically fall into two categories: hormonal and non-hormonal, such as devices that physically block sperm from coming out. “Non-hormonal is going to be the straightest path to a male contraception,” says Herati. “You really have to disrupt the exit points or signaling from different points of access. The hypothalamus signals to the pituitary which signals the testes — that’s what drives sperm production.”

Hsieh says that one option researchers are looking into is “reversible vasectomies — a device that allows temporary obstruction of the vas deferens [to block sperm] so it’s more reversible” than traditional vasectomy. Contraline is currently testing a non-hormonal reversible vasectomy, called Adam, which involves injecting a hydrogel into the vas deference under local anesthetic to block sperm. The gel, which can be monitored via ultrasound, eventually liquifies after about a year, per Contraline.

As far as potential hormonal options, they include a promising contraceptive gel for men called NES/T currently in phase II human clinical trials. The gel, applied to a man’s shoulders once per day, contains the hormones progestin (brand name Nestorone) and testosterone. Progestin blocks testosterone production in the testes, which slows sperm production to “low or nonexistent levels,” while replacing the body’s own testosterone to maintain the hormone’s normal functions, including sex drive.

Preliminary research presented at the Endocrine Society’s annual meeting in Boston on June 2 shows that the gel suppresses sperm production faster than similar experimental hormone-based methods for male birth control. Most study participants (86%) reached a sperm count of 1 million or fewer sperm per millimeter of semen — the threshold considered effective for contraception — by week 15. On average, however, sperm production was suppressed at eight weeks. It’s estimated that the trials will be completed by summer of 2024.

But others are still trying to develop that elusive male birth-control pill. YourChoice Therapeutics, Inc., for example, started phase one human clinical trials of YCT-529, with the goal of becoming the first hormone-free, reversible male birth control pill. In initial preclinical studies on animals, which received funding from the National Institutes of Health, researchers from the University of Minnesota found that the pill was 99% effective and 100% reversible with no reported side effects. The drug targets vitamin A, which plays a vital role in male fertility and the production of sperm. “You're disrupting a process or pathway that is integral to sperm development,” explains Herati, who is not involved in the study.

Other researchers are looking into non-hormonal reversible contraceptives that target sperms’ ability to swim, rather than the Herculean task of trying to suppress sperm production. A 2021 animal study found that taking a daily oral dose of a compound called triptonide — which comes from a Chinese herb or can be produced synthetically — affected the shape of sperm and its ability to move, consequently causing male infertility in as early as three to four weeks. Once treatment stopped, fertility returned in about four to six weeks.

Experts say that one of the biggest challenges to developing an effective male contraceptive is stopping the sheer volume of sperm that men produce each day: more than 1,000 sperm per minute.

“It’s the volume of sperm [while] women have a cyclical nature to ovulation,” Dr. Amin Herati, director of male infertility and men’s health and an assistant professor of urology at Johns Hopkins Medicine, tells Yahoo Life. “If you disrupt that and the hormones that fluctuate, you can disrupt ovulation. In men, you’re dealing with a process that is turning out hundreds of millions of sperm per day.”

If a male contraceptive blocks 99% percent of sperm, for example, “that’s a million sperm” still getting through, points out Herati.

Research shows that pregnancy prevention disproportionately falls on women in heterosexual relationships, so other challenges may include “a cultural attitude about contraception,” Dr. T. Mike Hsieh, a urologist and director of UC San Diego Health Men’s Health Center, tells Yahoo Life, and some men’s reluctance to take daily pills. In addition, “some women may not be comfortable with men being in charge of pregnancy prevention” and relying on them, notes Hsieh.

That said, research shows men do want new methods and are willing to try them. A 2021 review of multiple studies looking at attitudes toward new male birth control options found that “there is consistent interest among both men and women” and a “willingness to use them.” In new drug trials, 34% to more than 80% of male participants were open to using a male contraceptive. The research also showed that “both men and women expressed the desire to share responsibility for contraception.”

Hsieh points out that post-Roe v Wade, as several states in the U.S. have imposed abortion restrictions or bans, there’s been “a significant increase in interest” in vasectomies — not surprisingly, “significantly more in states with very strict anti-abortion laws compared to more liberal states,” he says — which might also help increase the urgency for more male contraceptives to come to market.

“Maybe the Roe v Wade decision is what it takes to push to explore more male contraceptive options,” Hsieh says.

After all, Herati points out that there should be “some responsibility” on both sides when it comes to family planning and pregnancy prevention. “It takes two to tango,” he says.

This article was originally published on December 19, 2023. It has since been updated.