A drug dubbed JQ1 swiftly stunted sperm production in male mice, a new study found. And like the female birth control pill, its fertility-fighting effects on were completely reversible.

"We have only observed full recovery of fertility in treated males," the researchers from Baylor College of Medicine wrote in their study, published today in the journal Cell. "We envision that our discoveries can be completely translated to men, providing a novel and efficacious strategy for a male contraceptive."

JQ1 blocks a protein essential for sperm production in the testes. If the drug is proven to be safe and effective in humans, it could expand the prophylactic pool -- an exciting prospect at a time when over a third of U.S. pregnancies are unintended.

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