Male Contraception that is 100% effective and lasts for years

RISUG (which is an acronym for “Reversible Inhibition of Sperm Under Guidance”), called Vasalgel™ in the U.S., is similar to vasectomy but with one significant advantage: it is more easily reversible. Researchers achieve this feature by injecting a polymer (a gel) into the vas deferens, rather than cutting the vas (as is done in vasectomy). The polymer then coats the inside walls of the vas deferens and kills sperm as they go by. If a man wishes to restore fertility, whether after months or years, the polymer is flushed out of the vas with another injection. This method could thus be ideal for men who think they are finished having children but would like the chance to change their minds in case of remarriage or the death of a child—and it could possibly even be appropriate for men who want child-spacing or young men who want to complete their schooling before having children.

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My dad's girlfriend's brother reversed a vasectomy.

Yeah, no chance in hell am I going to get an injection into my balls

awesome, anything to reduce the ridiculous rate we keep multiplying at. I'd happily see it injected into all newborn males like a vaccination, and then only when they decide that they 100% definitely want to father a child would they seek out the second injection.

What the hell is the point in that? Did you miss sex ed when they talked about puberty?

because then every future man would automatically have it. no making accidental babies. Same thing as circumcision - nobody cares if it's done to babies, but how many un-cut grown men would volunteer for it?

because you'd be putting gel into something which doesn't work at all. All sorts of things could go completely wrong and no research body would allow researchers to do this to newborns to determine the side effects.