Any child born today from a UK sperm donor will have little trouble finding his biological father in the future — Britain’s national sperm bank has just admitted that it only has nine registered donors. But Laura Witjens, the chief executive of the sperm bank, says it's currently working on trying to rectify the donation shortage in order to meet increasing demands.

Witjens says there may be a few reasons for the shortage, which new advertising plans will try to work against. For one, the UK national sperm bank is still relatively young; it was started last year thanks to a one-off award of nearly $118,000 from the National Gamete Donation Trust and Birmingham Women’s Hospital. Along with this, recent anonymity laws have changed, potentially discouraging donors from visiting facilities. As of 2005, any child who has turned 18 and was born from a sperm donor is allowed to trace their biological father to try and make contact. No cases have been reported yet, but some are expected during 2023, which will be 18 years after the law was passed.

Aside from all of that, it’s also time consuming to become a donor. “If 100 guys inquire, 10 will come through for screenings and maybe one becomes a donor,” Witjens told The Guardian. “It takes hundreds of guys.”

To donate, a man is required to make a donation twice a week for up to four months. He is also asked to refrain from sex or masturbation for the two days before each clinic visit, and follow up six months later for another test. To top it off, he must have sperm strong enough to withstand being frozen, which is more difficult than it sounds.

Donors may also feel that what they earn is not enough to compensate for their time. Currently, a donor gets paid about $54 per session, but Witjens says that giving more money is not the answer. “We might get more donors in if we paid them [$75], or [$153] per donation. But money corrupts. If you feel you can make [$300] a week for four months, you might hide things about your health.”

Unfortunately, this shortage has proven to be a big loss for many couples looking to conceive using donor sperm. Thanks to changes in same-sex marriage legislation, an increase in same-sex couples looking for donors has put a strain on the market. According to 2013 figures from the Human Fertilization and Embryology Authority, there has been a 20 percent increase in same-sex couples receiving donor insemination. These numbers still reflect times before the legislation was enacted, suggesting that number has increased even more.

Moreover, many of those requesting sperm donors have high expectations, Witjens said. “We get asked for 6-foot-tall donors, when the average height is 5 feet, 7 inches in Britain, so you are effectively ruling out 90 percent of the donors,” she said. “And they all want doctors or barristers, but the reality is the majority of those professionals have not got time. So you actually get young guys with flexible jobs.”

In order to get more donations, Witjens thinks that using Denmark’s advertising tactics may hold the answer. Danish sperm banks often attract donors by appealing to their masculinity, and vanity, and so far it’s working.

“If I advertised saying, ‘Men, prove your worth, show me how good you are,’ then I would get hundreds of donors,” said Witjens. “That’s the way the Danish do it. They proudly say, this is the Viking invasion, exports from Denmark are beer, Lego, and sperm. It’s a source of pride.”

To mimic this strategy, Witjens has proposed a type of Superman-themed advertising to appeal to this side of men, while also emphasizing that only the strongest sperm will survive after being frozen. As for the proposed campaign, although it has yet to be finalized, it isn’t as blunt as the Danish campaigns. She says that right now they plan to use real men for the commercial, though the picture on their pamphlet will be of a superhero character.

Witjens also notes that a campaign centered on male pride rather than altruism could pose a moral dilemma: Future children of these donors may not be happy to find that they were a product of a marketing scheme to display masculine prowess.

Ultimately, Witjens and the national bank hope that increasing donor numbers through advertising will stop people from seeking donations from foreign banks. British banks are preferable, she said, because they limit the number of children that can be conceived from one donor. Those who don’t limit this may cause problems for future children. “It’s always a very real fear for the donor-conceived, running into a half-brother or sister.”

For now, the UK national sperm bank has high hopes for the future. “I want to get to a stage where there is an abundance of donors, so no woman ever feels she has to go on Gumtree to get sperm,” Witjens said. “We can get there, we can have enough in three to five years. We just need the push.”