Cornell Scientists Develop Promising Male Contraceptive

Proof-of-concept study in mice shows safe, reversible method to stop sperm production.

Apr. 8, 2026 at 6:44am

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A vibrant, neon outline of a human sperm cell against a dark background, conceptually representing the breakthrough in male contraceptive technology.A revolutionary new approach to male contraception aims to safely and reversibly halt sperm production.Ithaca Today

Cornell University researchers have made a breakthrough in developing a safe, reversible, and 100% effective nonhormonal male contraceptive. In a study on mice, they found that targeting a natural checkpoint in meiosis, the process by which sex cells reproduce, can safely stop sperm production without long-term effects. The researchers used a small molecule inhibitor called JQ1 to disrupt prophase 1 of meiosis, cutting off the onset of gene expression required for sperm production. After stopping the treatment, the mice regained normal sperm function and fertility, and their offspring were healthy.

Why it matters

Currently, male contraceptive options are limited to condoms and vasectomies, which many men are hesitant to undergo. Hormonal contraceptives have proven potentially dangerous in women, so researchers have been reluctant to develop them for men. This new approach targeting meiosis could provide a safe, reversible, and highly effective alternative for male birth control.

The details

The Cornell researchers made use of JQ1, a small molecule inhibitor developed as a research tool to study cancer and inflammatory disease. While JQ1 has neurological side effects that make it unsuitable as a final contraceptive, it was able to disrupt prophase 1 of meiosis, enabling the team to demonstrate that meiosis and sperm production can be safely and reversibly targeted. In the study, male mice were administered JQ1 for three weeks, resulting in a complete halt of sperm production. When the treatment was stopped, normal sperm function and fertility returned within six weeks, and the mice's offspring were healthy.

  • The proof-of-principle study in mice was six years in the making.
  • The researchers administered JQ1 to male mice for three weeks.
  • Within six weeks of stopping the treatment, the mice regained normal sperm function and fertility.

The players

Paula Cohen

Professor of genetics and director of the Cornell Reproductive Sciences Center.

Cornell University

The institution where the researchers conducted the study on developing a safe, reversible male contraceptive.

JQ1

A small molecule inhibitor developed as a research tool to study cancer and inflammatory disease, which was used in the study to disrupt meiosis and stop sperm production in mice.

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What they’re saying

“We're practically the only the group that's pushing the idea that contraception targets in the testis are a feasible way to stop sperm production.”

— Paula Cohen, Professor of genetics and director of the Cornell Reproductive Sciences Center

“Our study shows that mostly we recover normal meiosis and complete sperm function, and more importantly, that the offspring are completely normal.”

— Paula Cohen, Professor of genetics and director of the Cornell Reproductive Sciences Center

What’s next

The researchers say a male contraceptive would likely start in the form of an injection taken every three months, or possibly a patch, to ensure effectiveness.

The takeaway

This breakthrough in developing a safe, reversible, and highly effective nonhormonal male contraceptive could provide a much-needed alternative to the limited options currently available, potentially empowering more men to take an active role in family planning.