In March, researchers got excited about a "significant advance" in developing the most elusive of contraceptives: a birth control pill for men.
News of this advancement makes the rounds every few years, but more than 50 years since the FDA approved oral contraceptive for women, a male equivalent hasn't hit pharmacy shelves.
Here are a few highlights in the hunt for a male contraceptive revolution:
Herbs and hemp seeds
Natural materials such as hemp seeds and the cotton plant Gossypium herbaceum have been touted as male contraceptives for centuries. A gossypol compound has been pursued as a male contraceptive, but studies found the effects irreversible in around 20 percent of men and potentially toxic.
Ultrasound—applied to the testes—has been tried on male rats, cats, dogs, monkeys, and some humans over the past few decades. The studies revealed that the treatment reduces the number of sperm, but more work is needed to measure effectiveness, longevity, and reversibility. The question of whether men would actually be willing to receive regular ultrasound treatments remains.
Vasalgel probably stands as the most promising male contraceptive to date. Based on "reversible inhibition of sperm under guidance," it requires injecting the vas deferens (the duct that sperm travels through from the testicles to the urethra) with a polymer so no sperm can pass. Trials in India with animals and humans have shown promise, but US trials are still required for FDA approval.
Contraceptive pills regularly crop up in science journals. The latest proposal, from scientists at the University of Minnesota, suggested tweaking the chemical structures of compounds known to interact with receptors involved in male fertility, to avoid some of the side effects associated with hormonal methods. Trials to prove its efficacy and safety are necessary, of course.
Meanwhile, the future of fertility is evolving in other ways. With continued advances in in vitro fertilization, it's conceivable that family planning could one day accelerate beyond reversible contraceptives, leaving the idea of a male pill as a forgotten retrofuture—and allowing sex to be purely a leisure activity.