Edinburgh University scientists have discovered a gene that is key to the production of sperm.
A drug that blocks the gene from working could be used as a contraceptive, liberating women from the burden of family planning.
The research could also lead to a 'genetic vasectomy' - a jab of genes that would leave a man permanently sterile.
Ultimately, within just five to ten years, it could even mean new treatments for infertile men, allowing them to achieve their dream of fatherhood.
The hopes come from an early-stage study in which scientists bred mice in which a gene called Katnal1 didn't work.
This left the male animals infertile. Tests showed that Katnal1 affects a key stage of sperm development, in which 'nursemaid' cells in the testicles nurture and nourish sperm as it matures.
If Katnal1 doesn't work properly, the sperm don't fully mature, the journal PLoS Medicine reports.
The discovery paves the way for drug that temporarily stops the gene from working.