How the 'male pill' could actually work

Story highlights

  • Oral contraceptives for men are in development
  • Japanese researchers have made mice reversibly infertile
  • Also being trialled are injections that block sperm from leaving a man's body

Vital Signs is a monthly program bringing viewers health stories from around the world.

(CNN)"The Pill" -- two words synonymous with birth control. But more than 50 years after oral contraceptives became commonplace, they remain an option only available to women.

In the United States, 17.5% of women aged 15-44 using birth control are taking oral contraceptives, according to the U.S. Centers for Disease Control (CDC).
For men, the options remain as they have done for centuries -- condoms and vasectomies. There is no pill in sight. Yet.
    "Even if just 5-10% of men used this (an oral contraceptive), it would limit population growth," says Ilpo Huhtaniemi, emeritus professor of Reproductive Endocrinology at Imperial College London.
    The permanence associated with vasectomies means they're more popular with older men, while younger males prefer condoms. "There has to be something for men to take responsibility in the same