Why isn't there a male birth control pill?

No male birth control product has made it to market, but over the past year, there has been promising early progress on new treatments — including a pill, a gel that’s rubbed onto the skin and an injection that acts as a nonsurgical vasectomy —that could finally bring the first male contraceptive to the public. If that happens, research suggests a "male pill" could drastically reduce unplanned pregnancies, especially in developing countries.