Though sperm donation is gaining ground in China, fears about potential incest and other social taboos are keeping many potential donors away from the clinics, say experts.

Candy, a 34-year old Chinese woman, who only wants to be quoted by her English name for privacy, has been married for five years and is desperate to have her own child. Though regular check-ups revealed no major problems, her problem arose as her husband's sperm had low vitality, or in other words as much as 99.9 percent of the sperm was dead.

Though the couple tried every possible means to improve the quality of the sperm, including a surgery, a course of traditional Chinese herbal medicine and even the advanced in vitro fertilization, nothing much happened. Till date the couple have spent about 300,000 yuan ($46,333) on various procedures.

Traditional Chinese families often blame infertility on the women and it was not uncommon for marriages to fall apart if the wife was unable to deliver a child.

Though such things still happen in some rural areas, modern medical science has proved that infertility can be prevalent in both men and women with equal probability, say a study published by the National Health and Family Planning Committee.

Wang Biqin, a senior gynecologist specializing in treating infertility with traditional Chinese medicine at Beijing University of Chinese Medicine's Dongzhimen Hospital, says women's infertility has led to many divorces.

"If the man has reproductive problems, but the woman is healthy, usually the marriage lasts." Wang says. "But when the woman is infertile, the man often leaves her," says Wang.

Candy says her husband and her in-laws have shown great support for her, financially and spiritually, as they know it is not her fault. Her husband says it'll be absolutely her call to decide whether or not to even have a baby, as long as she is happy.

"Men mature late," says Candy. "He might not want a baby at his age, but when he gets to 40 or 50, I am sure he will change his mind. We will regret it then if we don't try now."

The determined wife says she will keep trying for at least another decade, but she is strongly opposed to the idea of using a donor sperm.

Candy has discussed this with her husband and has reached an agreement that, if in the end they cannot have their biological baby, they would choose to adopt a child rather than turn to a sperm bank.

"My husband's father was adopted, and he proved to be a very reliable and dutiful son. So our whole family believes that an adopted child can be as good as a biological one," Candy says.

Candy's concern about the risk of incest from using unknown sperm is common. Online surveys conducted by the Beijing-based official Human Sperm Bank affiliated to the National Health and Family Planning Committee show that this is one of the major reasons why people are hesitant about sperm donation.

Not only do donors and recipients worry about this, but also regulators around the world.

In China, the government has implemented strict regulations to limit the use of sperm banks: Sperm from an individual donor can be used to fertilize eggs from just five women.

Liang Xiaowei, director of the Beijing-based sperm bank under the NHFPC, says that given the huge population in China, the five women restriction will statistically minimize the chance of a donor's biological children having intercourse with one another.

"The calculation is correct. The probability will be much lower than that of naturally-happening and unintentional incest." Liang says. "Even if we lift the upper limit to eight to 10 women, the chance will still be lower than the average."

Calculations aside, there are at least two challenges here. One is, as the donors and recipients are strictly prohibited from knowing about each other in China, it is virtually impossible to prevent a pair of biologically related brother and sister from getting married, if by any chance they fall in love.

Liang says that her sperm bank keeps record for 70 years of the whereabouts of the donors' sperms to the point till their recipients have babies. Each baby produced via this sperm bank will get their unique identification number, which is confidential.

However, in reality, most parents who receive sperm donation tend to keep the process secret, especially from their children. Liang says her sperm bank has never received any request of such examination in the past decade, and she doubts whether this service will be used in the future.

The second challenge is, how to ensure a donor's sperm is used in different regions across the nation, rather than within one city, like Beijing. The latter arrangement will statistically increase the probability of the donor's children running into each other.

Gao Shiyou, director of the reproduction center of the Hunan Provincial Maternal and Child Healthcare Hospital, says most of the sperm banks are established under reproduction centers of big hospitals and hence get most of the supplies.

"We all know the farther and wider we deliver the donors' sperms, the better it is." Gao says. "But the reality is, local demand for donations is huge and the supply is not enough. The existing sperm banks just cannot cater to the demand."

There is no specific law or governmental regulation that forces hospitals to diversify the recipients.

Gao feels that sperm banks should reach consensus among themselves to share a fixed proportion of their donations to other regions and vice-versa. "The larger the population base is, the safer it is." Gao says.