A global clinical trial on male hormonal contraceptive shots has proven effective for 96 percent of patients. By the end of the trial, 75 percent of men said they would be willing to continue receiving the shots as their primary method of birth control. This puts researchers closer than ever before to offering viable male hormonal birth control.
There was a fairly high occurence of side effects and adverse reactions reported in the study, although most were minor. Dr. Mario Philip Reyes Festin of the World Health Organization, who was the lead author of the study, said scientists may need to re-formulate the shots and try different injection protocols before further testing, for this reason.
“More research is needed to advance this concept to the point that it can be made widely available to men as a method of contraception,” he explained. “Although the injections were effective in reducing the rate of pregnancy, the combination of hormones needs to be studied more to consider a good balance between efficacy and safety.”
The study notes that researchers have been experimenting with reversible hormonal contraceptives for men for four decades, and have been unable to offer a safe and reliable option. Surveys among both men and women have demonstrated a high demand for such a product, although they have shown a pill would be preferable to an injection for most men.
The trial studied 320 men in Australia, Germany, the UK, Chile, India, Indonesia, and Italy, who were healthy and between the ages of 18 and 45 years old. The men were also in stable, long-term relationships with healthy women. The men’s sperm levels were tested first, before being suppressed by a hormone injection every 8 weeks, for a total of 26 weeks. When sperm levels were found to reach a low concentration level, the couples were allowed to stop using backup birth control methods. They continued using the shots for birth control for about a year, at which point the men entered a recovery phase, during which doctors observed their sperm levels to make sure they returned to normal.
of 320 participants, 274 reached low enough sperm levels to stop using other birth control. Out of the 274, 266 stayed involved with the study. Out of these 266, four impregnated their partners by the end of the study – with an efficacy rate of 2.2 pregnancies per 100 women. As a point of reference, proper condom use yields an efficacy rate of 3 to 5 pregnancies per 100 women.
Side effects included depression and other emotional issues, acne, muscle pain, and increased sex drive. The vast majority of the emotional side effects were reported from a single study center in Indonesia, suggesting a cultural component in the way the effects were perceived. In contrast, study participants in India reported very few adverse reactions, and acne effects were distributed fairly evenly throughout the areas studied.
Most participants returned to normal fertility levels within one year after the conclusion of the study.