Part of the problem is down to our system, with donor recruitment generally carried out on a small scale in British fertility clinics. On average, just one in every 20 men who applies will be suitable to donate. Men do not only need to have high-quality sperm: they also have to undergo a full range of screening tests for genetically inherited diseases and sexually transmitted infections, and their family medical histories must be assessed. Those deemed suitable will need to commit to regular visits to the clinic, usually during the working day. It’s often easier for a clinic to suggest their clients use a Danish donor, where a specialist sperm bank has the resources to devote to finding the 5 per cent who fit the bill.