In Britain, as in many countries, there is a growing demand for sperm donors from couples who are unable to conceive on their own. Increasingly, demand is outstripping supply.
Last year, the British government came up with a solution: Set up a national sperm bank to make it easier for couples to get access to medically checked sperm.
But it has not been easy finding suitable donors.
A year later, and with more than 600 applicant donors, the bank still has just nine approved donors. According to Laura Witjens, the executive director of the bank, that should be a cause for celebration, rather than disappointment. "I recognize that people say 'Nine? That's not a lot," She says. "But I like to turn it round, and say: 'At this stage to have nine? Wow!" It's a great place to be".
Part of the problem stems from the extreme difficulty of finding men whose sperm can withstand the demands of the donor process. Freezing and defrosting the samples destroys 80 to 90 percent of even successful donors' sperm.
There is also the time and commitment required from each donor. Samples need to be taken several times a week for two or three months. That's followed by blood tests.
But perhaps the biggest difficulty in recruitment lies in the British law regarding donor anonymity. Under current rules, there is none. In the future, British children conceived from donated sperm will be able to trace and contact their biological father once they reach adulthood. Given the limited number of approved donors in the national bank, that could mean that each donor has the potential to be contacted by a large number offspring over the next few decades.
Witjens concedes that this may make some men reluctant to become donors, but she says it also forces her team to think more carefully about how to appeal to donors.
"It would be easy to go for the cheeky advertising, and I know that would get a response," she explains. "But there is a moral component. We don't necessarily need a superman, we need ordinary men, doing an extraordinary thing: Be willing to help childless couples."