BRITAIN’S first national sperm bank opened to the public in Birmingham on October 30th: a sign that the country is at last dealing with the fact that demand for sperm donors far outstrips supply.

The number of single British women seeking sperm rose by 55% between 2000 and 2012, which was also the first year in which more women over 45 used donor eggs than used their own. Various factors explain the trend. The main one is that women’s greater financial independence has increased the appeal of in vitro fertilisation (IVF), one of the uses for donated sperm. They are under less pressure to settle with a partner and more able to fund single motherhood. Another reason is the rise (by 17% between 2010 and 2011) in the number of lesbian couples undergoing donor insemination. The age at which women have children has also risen slowly since the 1970s. And yet the annual number of new sperm donors grew from 375 in 1992 to just 586 in 2013; not much for 25 years of encouragement. Figures released this week by the Human Fertilisation and Embryology Authority show that one-third of Britain’s newly registered sperm donors last year were abroad.

Why the shortage? Donating sperm is a convoluted process that requires tests and clinic visits over many months. Giving eggs is even tougher: it requires surgery. But donors’ compensation is meagre. British sperm donors get £35 ($56) each time (Americans get $75) and British egg donors receive £750 per donation cycle (Americans can earn up to $10,000). Moreover, a change in the law regarding anonymity means children can now track down their biological parents. In 2004, the year before it came into force, the number of new sperm donors fell to 239. In the United States and Denmark, by contrast, donation remains anonymous.

Britain may be hampering recruitment in other ways, too. Denmark’s slogans encouraging sperm donors are compellingly macho and patriotic: “These are the main Danish export products—beer, Lego and sperm!”, and “Congratulations, it’s a Viking!” The London Sperm Bank settles for the rather less inspiring “Lend a hand”. Laura Witjens, CEO of the National Gamete Donation Trust, says that campaigns have focused on altruism, not masculinity, as “we don’t want to imply that infertile men are any less of a man”. Still, Britain is doing better than the Netherlands, which barely bothers to advertise.

For an ageing population like that of Britain, it would be wise to provide enough sperm to women who want it. Denmark’s population would be shrinking were it not for IVF babies: they accounted for 3.9% of births in 2003. In Britain, that figure was 1.5%.

The new sperm bank will be a step forward. It intends to cut the cost of buying sperm to around £300 per sample. Birmingham’s diversity could help meet demand for ethnic-minority sperm, a specific area of shortage. And it will supply clinics equally, which should reduce inequality between donation-rich urban areas and those where supplies are scarce. The bank still needs help, however, making sperm donation sound desirable. Its slogan? “Open your account today.”