Despite repeated efforts to recruit more donors, almost three decades after China opened its first sperm bank, such fertility institutions are dealing with a worsening shortage of healthy sperm.
"It feels weird to know that someone you meet on the street some day could be your child," said Zhou Zheng, a sperm donor from north China's Hebei province.
Zhou now has complicated feelings about the donation he made a decade ago, Xinhua reported.
Back then, Zhou was a college student who decided to donate sperm out of compassion for reproductively challenged couples. But the thought of being the biological father of a child he does not know scared him away from doing it again.
According to Chinese law, sperm donated by one person can be used to impregnate up to five women. This means that Zhou, who is married with his own child, could actually have as many as six offspring.
"Knowing I might have five other kids out there really freaks me out," he said.
Statistics from the China Population Association at the end of 2012 showed that 40 million people have fertility issues, accounting for 12.5 percent of the population aged between 20 to 49. The ratio increased from three percent two decades ago.
China's first sperm bank opened in central Hunan province.
But at the Hebei Human Sperm Bank, qualified sperm is in shortage.
The sperm bank's director Zhao Bangrong said there are currently 700 couples waiting for sperm, but the bank only had 200 volunteer donors in the first six months of the year, compared to 650 volunteers during the same period last year.
Not all volunteers can donate. Only 20 percent meet the requirements set by health authorities.
People with hereditary diseases or those who have been exposed to radioactivity, or those who have a history of heavy smoking or drinking, are not permitted to donate.
People also incorrectly assume that being disqualified for donation means they have reproductive problems. Such fears have driven potential donors even further away.
Another factor is cultural perceptions. Some do not think of donating because they believe it amounts to betrayal of one's ancestral bloodline, which according to traditional beliefs should be preserved within one's family.
In China, sperm donation is also somewhat embarrassing in a society that still struggles with public discussion of sex-related topics.
Environmental pollution, unsafe food and mounting work pressure are all reducing the odds of a successful and healthy pregnancy, doctors say.
Sperm shortage and growing infertility have also spurred illegal insemination in the underground market.
To ease the shortage, sperm banks across China have launched campaigns to show sperm donation in a better light and attract potential donors.