A New Sperm-Blocking Male Birth Control Method Is Being Put to the Test

Women have far more control over their bodies today than we did before the pill was invented. But reproduction is a two-player game, and women still carry a far greater burden than men when it comes to preventing unwanted pregnancy.

A Virginia-based startup called Contraline is hoping to change this. The company developed a new type of contraceptive for men, and just implanted it in four people as part of an initial clinical trial.

You Shall Not Pass

Unlike male birth control pills that have undergone clinical trials in the past (unsuccessfully, it seems), Contraline’s method doesn’t involve hormones, and its aim isn’t to decrease or stop sperm production. Instead, it blocks sperm from getting to mens’ urethras, where it would ultimately be ejaculated—and possibly enter a woman, fertilize one of her eggs, and create a baby.

Sperm are produced in the testes and stored in an adjacent organ called the epididymis. They’re carried from there to the urethra through a fibromuscular tube called the vas deferens. Contraline’s contraceptive works by blocking semen from getting through the vas deferens.

Called ADAM, the contraceptive comes in the form of a hydrogel, which is injected directly into the vas deferens in an outpatient procedure that uses local anesthesia and takes less than 30 minutes. Without affecting sensation or ejaculation, the gel acts as a barrier to sperm flow, blocking it from traveling through the tube. The blocked sperm naturally degrade. At the end of the gel’s lifespan it liquefies, allowing sperm to resume flowing through the vas deferens.

vas deferens sperm blocker contraceptive Contraline
Illustration showing how ADAM works: a hydrogel injected into the vas deferens blocks sperm from passing. Image Credit: Contraline

Making Moves

Four men received injections of ADAM at a hospital in Melbourne, Australia last week. Doctors will monitor the recipients’ semen parameters over the next three years, and keep a close eye on the contraceptive’s safety.

Side effects reportedly include mild pain and minimal swelling, though it’s unclear whether these only occur post-injection or are longer-lasting. These aren’t bad compared to what many women go through.

Contraline recently closed a $7.2 million funding round led by GV, bringing the total it has raised to date to $17.9 million. The Melbourne study also received funding from the Male Contraceptive Initiative, a group that advocates for research and development in male birth control.

Contraline’s next goal is to get a larger clinical trial underway in the US, and to get its product approved by the FDA. If that happens, the company would develop various versions of ADAM that differed in longevity; there could be a one-year option and a two-year option.

The Competition

There’s at least one hormonal contraceptive in the works for men. Nestorone is a gel men apply to their shoulder blades (of all the parts of the body, this seems like an odd choice, both in terms of ease of application and proximity to the area in question—but hey, the body works in mysterious ways).

The gel contains hormones that inhibit testosterone production in the testicles while maintaining blood testosterone levels so that there’s no negative impact on men’s libido or sexual function. This past summer saw the completion of a one-year clinical trial with 100 couples. The study aims to enroll 320 more couples, reaching completion by the end of 2024.

Towards a New Normal

Getting men to share the burden of birth control will take more than simply having viable options available, though. Since female bodies are where pregnancy occurs and the pill has been around since the 60s, the predominant line of thinking is that women are responsible for keeping our bodies from making a baby. The side effects that come with hormonal birth control can be severe—from weight gain to headaches, nausea, low libido, and bleeding—but they’ve come to be regarded as part of the deal.

How long might it take for men to not only get used to the idea of male birth control, but willingly partake in it? According to the American Society of Andrology (‘andrology’ refers to the medical specialty that deals with male health), multinational survey data says 29 to 71 percent of men would use a male hormonal contraceptive. That’s a pretty wide and not very conclusive range, which could be reflective of varying sentiment between different countries and cultures.

Maybe we’ll be pleasantly surprised, though. According to Kevin Eisenfrats, Contraline’s cofounder and CEO, the company saw no shortage of men willing to try its product. “The patient demand for the ADAM Study has been tremendous, with the entire trial oversubscribing within three weeks of opening enrollment,” he said in a press release. “We are looking forward to advancing ADAM through clinical development and bringing this product to market to transform how people think about contraception.”

Image Credit: geralt / 25256 images

Vanessa Bates Ramirez
Vanessa Bates Ramirez
Vanessa has been writing about science and technology for eight years and was senior editor at Singularity Hub. She's interested in biotechnology and genetic engineering, the nitty-gritty of the renewable energy transition, the roles technology and science play in geopolitics and international development, and countless other topics.
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