Researchers from the Beijing-based Chinese National Research Institute for Family Planning have reported a method for male contraception that they say is effective, reversible and without serious short-term side effects.

In the testing conducted with nine other research centers around China, 1,045 healthy fertile males were injected monthly with 500 milligrams of a formulation of testosterone undecanoate in tea seed oil during a course of 30 months. During the 24-month study period, only 1.1 men per 100 experienced contraceptive failure.

After the hormone treatment, the participants’ sperm count returned to normal levels. The tested men experienced mild side effects including weight gain and acne.

"For couples who cannot or prefer not to use only female-oriented contraception, options have been limited to vasectomy, condoms, and withdrawal," said Yi-Qun Gu, a professor with the National Research Institute for Family Planning’s research department. "Our study shows a male hormonal contraceptive regimen may be a potential, novel, and workable alternative."

The androgen works by dramatically reducing two regulatory brain chemicals, follicle-stimulating hormone and luteinising, which in turn disrupt sperm production.

The development could place male contraception on a par with the female birth control pill. However, Professor Gu cautioned that more extensive testing will be necessary to ensure long-term safety, particularly with regard to cardiovascular and prostate health.

Despite China’s one-child policy (which is not strictly enforced in rural areas), China’s population is projected to grow from the current 1.315 billion to 1.4 billion by 2015. The Chinese Government is striving to stabilze the population at 1.45 billion by 2020.

Based on sources including Worldwatch Institute