A simple birth control method for men is about to begin testing, with researchers hoping a new topical gel will give men an alternative to contraceptive method outside of vasectomies and condoms. Clinical testing is set to begin in April as the National Institute of Child Health and Human Development, a division of the National Institutes of Health (NIH), will conduct the largest U.S. effort to test a hormonal birth control for men. The gel itself can simply be rubbed onto the user's skin, although the researchers suggest that it not be placed directly on one's genitals. The same team of researchers conducted a 2012 trial that combined the application of two gels and the the number of sperm in the test subjects' semen dropped to less than 1 million per millilitre, MIT Technology Review reports. That number is far below the average 15 to 200 million sperm per millilitre that would actually decrease chances of fertility. The six-month study showed the gel method to be effective in reducing fertility.