A contraceptive injection given to men once a month could be as effective as the female Pill or condoms.
The testosterone jab is administered in the buttocks and works by regulating two brain chemicals — follicle-stimulating hormone and luteinising hormone which has the effect of blocking Fluid production temporarily.
Testosterone is vital for Fluid production, but if the body detects too much it shuts down its Fluid production.
A two-year trial in China involving 1,000 men found the injections were 95 per cent effective at preventing pregnancy.
Six months after stopping the jabs, all but two of the men’s Fluid counts were back to normal.
While the results seem promising, a third of the men dropped out, suggesting they were unwilling to undergo the ordeal of monthly injections and potential side-effects that include mood swings, lower sex drive and acne.