The list of effective contraception is long. But it relates almost exclusively to women. Male contraception has remained a neglected area in the study field of human reproduction. Besides condoms and vasectomy, no other methods target the male side of the spectrum specifically. This rather unfortunate inequality could soon be resolved: now more research teams are striving to further involve men in controlling fertility. One of them announced on October 25 that a new strategy will be available by 2021. Researchers from the University of Wolverhampton (UK) have developed a pill for men that also comes in the form of a nasal spray.
Developed along with a Portuguese team, this method acts directly on sperm motility: it makes the sperms immobile, preventing them from reaching the egg to fertilize it. A fully reversible effect since it only lasts a few days. To believe the researchers, the method acts quickly. In pill or spray, it should be used just before sex. Its action takes effect after a few minutes.
Besides this very enthusiastic news, male contraception is also often talked about in the scientific literature. The Journal of Clinical Endocrinology & Metabolism has indeed published a clinical phase II trial that assesses the safety and efficacy of an intramuscular injection of two hormones: norethisterone (a long-acting progesterone) and a form of testosterone . The approach is quite different from the one mentioned previously. Indeed it acts to reduce the number of sperm produced and released during ejaculation.
320 healthy men took part in this test. Aged between 18 and 45, they were to be monogamous with a woman of reproductive age. Throughout the research, they delivered regularly sperm samples.
The first phase consists of a ramp-up: for 26 weeks, injections were performed to reduce sperm count below the threshold of one million units per milliliter of ejaculation. Then, two injections were prescribed every eight weeks.
Couples could abandon the emergency contraception only after the minimum threshold of sperm count was reached. For 274 for men, this level was reached after 24 weeks. Thereafter, only 4 pregnancies were reported. This corresponds to a rate of 1.57%. “The contraceptive efficacy is high, especially if compared to other reversible methods in humans; it is comparable to the effectiveness of a female oral contraception,” the authors say.
Not surprisingly, the approach must be further refined as the side effects are heavy. Depression and mood disorders are still too frequent. Others seem easier to live with: an increase in libido is possible. However, satisfaction remains high with 75% of participants say they are ready to continue the long-term male contraception. “The combination of hormones should be investigated further in order to develop a good balance between safety and efficiency,” admits Mario Reyes Festin Philip, from the World Health Organization – which is partially funding the study.
The study was financed by the United Nations Development Programme, the United Nations Population Fund, UNICEF, the World Health Organization, the World Bank Program for Research, Development and Training in Human Reproduction, CONRAD — which is itself partially funded by the Bill & Melinda Gates Foundation and the US Agency for International development. The laboratory Schering AG provided the injectable hormones.