A birth-control pill for men is now a reality, according to an international consortium of physicians who revealed their formula for "safe, effective and reversible" hormonal contraception for males.

The preparation includes progestin, a key ingredient found in women's birth-control pills, and the male sex hormone testosterone. Progestin, a synthetic version of a hormone produced in a woman's ovaries, helps suppress ovulation when used in an oral contraceptive. It appears to function in an analogous fashion for men, suppressing "both rate and extent" of sperm production.

Birth control remains a feminine affair for the most part. In developed countries, 73 percent of contraception worldwide involved "female methods," according to the United Nations" Population Division, which surveyed women of reproductive age in 160 nations. Condoms accounted for 13 percent and vasectomies 6 percent.

Some say men are ready for more participation, however.