In a move that could revolutionize birth control, scientists have designed a monthly testosterone injection that could be as effective as the female birth control pill. According to a report in the Journal of Clinical Endocrinology & Metabolism, trials that took place in China saw only 1 in 100 men father a child while taking the shot; six months after stopping the injections, their sperm counts were back to normal. The shots had no serious side effects, unlike previous attempts to develop a male contraceptive, which had problems ranging from reliability to lowered sex drive. Lead researcher Dr. Yi-Qun Gu, from the National Research Institute for Family Planning in Beijing, China, told the BBC: “For couples who cannot, or prefer not to use only female-orientated contraception, options have been limited to vasectomy, condom and withdrawal. Our study shows a male hormonal contraceptive regimen may be a potential, novel and workable alternative.” If further tests prove successful, it could become available as soon as five years from now.