And less effective than the pill?
A contraceptive injection for men has been shown to be almost 100 per cent effective, and may also increase libido.
The hormone-based jab is designed to lower sperm counts by acting on the brain’s pituitary gland.
Over a year-long trial, nearly 96 per cent of couples relying on the injection to prevent unplanned pregnancies found it to be effective. During this time, only four pregnancies occurred among the men’s partners.