Researchers from UCLA and the University of Sydney analyzed sperm data from male hormonal birth control studies conducted over the last two decades. They found that most men's sperm counts returned to normal within four or five months of stopping treatment.
"It is one thing to know that male hormonal contraception works, and another thing to know that fertility can be easily restored when a man chooses," says researcher Peter Y. Liu, Ph.D., M.D. "This is an important step in the evolution of male contraception."
In the more than four decades since women got the pill, the birth control methods available to men have not changed much.
The search for a safe, effective, and commercially viable hormonal contraceptive for men has been a slow one. But experts tell WebMD that scientific advances within just the last few years may soon give men more birth control options.
The version that appears closest to commercial reality combines an implant of the steroid hormone progestin and shots of another steroid hormone, androgen, says Diana Blithe, Ph.D. She is the program director for the National Institute of Child Health and Human Development's male contraceptive development program.
Progestins are often used in women's contraception. Androgens are the major hormones responsible for the development and maintenance of male characteristics.
The implant would last for a year; men would need to get the shots every three months. This is a big improvement over earlier versions of male hormonal birth control, which required androgen shots as often as every week.
"We are much closer than we were just a few years ago," Blithe tells WebMD. "Contraceptive formulations have improved and there is a general feeling that men will embrace this."
Return of Fertility
The newly reported research involved a review of the raw data from 30 studies of male contraceptives published between 1990 and 2005.
In all of the studies, sperm output was monitored every month after discontinuation of contraception until sperm recovery.
A threshold of at least 20 million sperm per milliliter of semen is a widely accepted indicator of fertility.