Among the methods Lissner deems the most promising:
How it works: The acronym stands for "reversible inhibition of sperm under guidance," and, while that's a mouthful, the method is pretty simple. A gel called a polymer is injected into the vas deferens, coating the vas deferens walls and killing sperm as they pass.
Why men might go for it: It's nonhormonal, and it's easily reversed (a second gel flushes out the polymer), making it an ideal choice both for young men who want to put off childbearing and older men who already have children but don't want to rule out having more in the future.
Why they might not: Studies have yet to determine exactly how long after an RISUG reversal pregnancy might be possible.
Status: Undergoing clinical trials in India.
How it works: Ultrasound waves heat the testes. In preliminary animal studies, 10 minutes of ultrasound provided about six months of contraception.
Why men might go for it: Simple, fast and long-lasting.
Why they might not: Not a home method.
Status: Small pilot studies are in progress.
Vitamin A Receptor Inhibitor
How it works: Nonhormonal oral contraceptive; preliminary studies in mice have revealed that seven days of treatment could provide 14 weeks of contraception.
Why men might go for it: Many men are uninterested in any type of hormonal contraception; an oral contraceptive without hormones could turn out to be one of the most user-friendly options on the table.
Why they might not: As women who have struggled to remember to take a birth control pill at the same time every day can attest, oral contraceptives that come with stringent schedules could be a tough sell.
Status: Toxicity studies are already complete because the drug was initially developed for a different use; researchers at Columbia University are looking for funding to begin contraceptive studies in monkeys.