Previously, only women are troubled with the problem of contraception to prevent pregnancy. Now, the man also responsible for birth control.

For years, scientists looking for the equivalent male contraceptive pill. In the 1990s found that weekly injections of testosterone reduce the sperm count as much as 98 percent. But, the effect disappeared when the injections stopped. So the researchers think that a weekly injection is considered unpopular and troublesome men.

Since that's the researchers conducted experiments with oil-based injections, which combines tea seed oil plus testosterone. And the effects of this injection lasted longer.

The new study shows that the 1045 men aged 20-45 years in China, which already has one child, the number of children has not increased. For six months, many people participate following the monthly testosterone injections in their buttocks. The result, most men have very low sperm count. In this way the failure rate of only about 5 percent.

However, testosterone injections have side effects such as rashes, pimples or changes in sexual drive. Dads, interested?