Is this the beginning of a male contraceptive?

Researchers testing a contraceptive injection for men see successful results

Researchers in the US testing a contraceptive injection for men found the jab to be almost 96% effective. The study, which was undertaken by 270 men, saw only four pregnancies among their partners in a year.

The men who participated were all between the ages of 18 and 45, and had been in monogamous relationships for at least a year. Their partners had all agreed to take part. The aim was the reduce the sperm count of each man from over 15 million per millimetre to under one million. To do this, the men were required to have two hormone injections every eight weeks, and were monitored for up to six months until their sperm count had fallen to the required level. Throughout the study, this was the only form of contraception used by the couples.

Despite its high success rate, a relatively high number of the men had side effects, including acne, mood disorders and muscle pain. Additionally, the men were monitored after they had stopped using the contraceptive to see how quickly their sperm counts recovered; eight of these men had not resumed normal levels a year after the study had ended.

Dr Mario Festin, of the World Health Organization (WHO) in Geneva, who carried out the study, said: “The study found it is possible to have a hormonal contraceptive for men that reduces the risk of unplanned pregnancies in the partners of men who use it.” He said other researchers were now looking at combining different levels of the same hormones, and delivering them in different ways.

Allan Pacey, professor of andrology at the University of Sheffield, said: “There is certainly an unmet need for an effective reversible contraceptive for men, along the lines of the hormonal contraceptive for women. However, none of the preparations that have been developed and tested to date have managed to become a commercial reality for one reason or another.”

He said the contraceptive in this study was “extremely effective and therefore certainly has promise” and that the number of side effects seen was a concern. Nevertheless, he added: “It is noteworthy that 75% of the men who took part in the trial would be willing to use this method of contraception again. So perhaps the side-effects weren’t all that bad after all.”

This study was published in the Journal of Clinical Endocrinology & Metabolism. Male hormonal contraceptives have been in research for around two decades, looking at how to suppress sperm production without causing unpleasant or unbearable side effects.