The sperm bank of Peking University Third Hospital is calling for healthy, young males to donate their sperm and pledges to reward each donor 5,000 yuan ($751) if the donation is successful.

The hospital, considered the best in Beijing, said it is in urgent need of 900 donors and volunteers can register between August and September on its official account on WeChat, a popular social media app, on Monday.

Volunteers must be Chinese, between 20 and 45 years old, living in Beijing at the time of donation and have no infectious diseases, such as hepatitis B or color blindness, according to the hospital. In addition, they are required to hold a junior college or a higher degree, the hospital said.

Each registered donor will have to undergo two physical checkups before donating, and he will have to donate at least 21 millimeters of sperm. He must finish the process within six months, the hospital said.

About 15 percent of married couples in Beijing and neighboring Tianjin are infertile, and 40 percent of them fail to get pregnant because of sperm problems. Due to high demand for sperm and lack of supply, couples in many places in China have to wait as long as two years for sperm, the hospital said.