But before you get too enthused, we need to mention that researchers are still working to optimize the combination of contraceptives to reduce the risk of mild to moderate side effects, including depression and other mood disorders.
In the study, 320 healthy, adult males, ages 18 to 45, received regular injections of the contraceptive. Twenty of the participants eventually dropped out, reporting issues which included mood disorders, such as depression, as well as muscle pain, injection site pain, and acne.
There was one death by suicide which was assessed not to be related to the use of the drug.
Co-author Mario Philip Reyes Festin, MD, of the World Health Organization in Geneva, Switzerland, says:
“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. Our findings confirmed the efficacy of this contraceptive method previously seen in small studies."
Few Options For Men
Better birth control options are needed for men. In 2012, 40 percent of all pregnancies worldwide were unintended, according to the Guttmacher Institute.
The participants in the study, from seven countries (Australia, Chile, Germany, India, Indonesia, Italy and the United Kingdom), had all been in monogamous relationships with female partners between the ages of 18 and 38 for at least a year. The men underwent testing to ensure they had a normal sperm count at the start of the study.
The men received injections of 200 milligrams of a long-acting form of progestogen called norethisterone enanthate (NET-EN) and 1,000 milligrams of a long-acting form of androgen called testosterone undecanoate (TU) for up to 26 weeks to suppress their sperm counts. Healthcare professionals gave the men two injections every eight weeks.
Participants initially provided semen samples after eight and 12 weeks in the suppression phase and then every 2 weeks until they met the criteria for the next phase. During this time, the couples were instructed to use other non-hormonal birth control methods.
Reduced Sperm Count
Once a participant’s sperm count was lowered to less than 1 million/ml in two consecutive tests, the couple was asked to rely on the injections for birth control. During this period known as the efficacy phase of the study, the men continued to receive injections every eight weeks for up to 56 weeks.
Participants provided semen samples every eight weeks to ensure their sperm counts stayed low. Once the participants stopped receiving the injections, they were monitored to see how quickly their sperm counts recovered.
The hormones were effective in reducing the sperm count to 1 million/ml or less within 24 weeks in 274 of the participants. The contraceptive method was effective in nearly 96 percent of continuing users.
Only four pregnancies occurred among the men’s partners during the efficacy phase of the study.
Researchers stopped enrolling new participants in the study in 2011 due to the rate of adverse events, particularly depression and other mood disorders, reported by the participants.
Despite the adverse effects, more than 75 percent of participants reported being willing to use this method of contraception at the conclusion of the trial.
The research was funded by the United Nations/World Health Organization, and the nonprofit organization CONRAD (Contraception Research and Development), using funds from the Bill & Melinda Gates Foundation and the U.S. Agency for International Development. The hormonal shots were provided by the pharmaceutical company Schering AG, which has since merged with Bayer Pharma AG.
Hermann M. Behre, Michael Zitzmann, Richard A. Anderson, David J. Handelsman, Silvia W. Lestari, Robert I. McLachlan, M. Cristina Meriggiola, Man Mohan Misro, Gabriela Noe, Frederick C. W. Wu, Mario Philip R. Festin, Ndema A. Habib, Kirsten M. Vogelsong, Marianne M. Callahan, Kim A. Linton, and Doug S. Colvard Efficacy and Safety of an Injectable Combination Hormonal Contraceptive for Men Journal of Clinical Endocrinology & Metabolism, October 27, 2016 DOI: 10.1210/jc.2016-2141