A Cornell University research team has developed a technique that can reversibly halt sperm production without affecting the body's hormonal system. The findings were published in the Proceedings of the National Academy of Sciences.

Development of male contraceptives has historically been slowed by hormonal side effects — methods that artificially lower testosterone can trigger acne, weight gain, mood swings, and reduced libido.

Professor Paula Cohen's team took a different route, targeting meiosis, the process by which sperm cells form, rather than manipulating hormone levels. Using a small-molecule compound called JQ1, the team selectively blocked a protein complex critical to sperm maturation, temporarily interrupting production without disrupting the body's broader hormonal balance.

In animal trials, male rats treated with the compound were unable to impregnate females, and sperm suppression occurred without damaging stem cells in the testes. Roughly six weeks after discontinuing treatment, normal sperm production resumed. Offspring born after treatment showed no physical or behavioral abnormalities and retained normal reproductive function.

The team is exploring long-acting injections and skin patches as delivery formats, which could offer lower failure rates than daily oral options. The research remains in the animal testing phase, with human clinical trials still requiring safety validation. Cohen is reportedly in the process of founding a biotech startup to commercialize the technology, with a target of initiating human trials within two years of launch.

A Cornell University research team has developed a technique that can reversibly halt sper …

Revolutionary Male Contraceptive: New Method Halts Sperm Production Without Hormonal Side Effects