In fact, 80 couples are taking part in the trial of the drug which the scientists say will be as effective as the Pill which is often linked to breast cancer and fatal blood clots, the ‘ Daily Mail ’ reported.
According to them, the contraceptive, given in two injections every two months, tricks the brain into shutting off sperm production in men.
It contains the male sex hormone testosterone and a man-made version of the female sex hormone progesterone and when the brain senses them, it reduces the levels of other hormones which control sperm production and maturation.
The scientists say it is effective in 99 per cent of cases and sperm counts should rapidly return to normal once the injections are stopped.
Prof Richard Anderson of Edinburgh University, who is heading one of two year-long trials, believes the jab will prove popular with both sexes. But because it will not protect against sexually-transmitted infections such as chlamydia, it is most likely to appeal to those in a committed relationship.
He said: “A lot of women may think it’s time men took their turn. When we carried out surveys of women, they were enormously enthusiastic. The single most common reason was they wanted to share the responsibility for contraception.”
Though no serious side-effects are expected from the jab, some men may experience hot flushes, mood swings or acne, the scientists say.
Dr Allan Pacey, a Sheffield University expert on male fertility, said male contraceptives had proved more difficult to develop than female ones but researchers were now “homing in” on the right combination of drugs.
He said: “Vasectomy is OK but although it is viewed as reversible it isn’t really, so it would be useful to have an alternative. The big sticking point is acceptability. I think there is a lot of education needed to convince men that this jab doesn’t make them less of a man.”
