New frontiers in nonhormonal male contraception

The world's population is nearing 6.8 billion, and we are in need of a male contraceptive that is safe, effective, reversible and affordable. Hormonal approaches, which employ different formulations of testosterone administered in combination with other hormones, have shown considerable promise in clinical trials, and they are currently at the forefront of research and development. However, the long-term effects of using hormones throughout a male's reproductive life for contraception are unknown, and it may take decades before this information becomes available. Because of this, many investigators are aiming to bring a nonhormonal male contraceptive to the consumer market. Indeed, there are several distinct but feasible avenues in which fertility can be regulated without affecting the hypothalamus-pituitary-testis axis. In this review, we discuss several approaches for fertility control involving the testis that one day may lead to the development of a nonhormonal male contraceptive.