New laws removing anonymity from sperm donors have led to a shortfall in recent years - there are just 208 in the UK. But, for many, it's hard to address the subject without raising a snigger - which is why comedian Danny Robins was asked to see if would-be donors might be persuaded.
I have to confess that until recently I knew nothing about sperm donation. Like many others, I suspect, I had no idea there was a crisis in donor numbers and, I guess, if I thought about sperm donation at all, it was as something a little bit seedy and embarrassing.
But then I met people like Siaran West, from Cardiff, who had been devastated when her husband's multiple sclerosis prevented them from having a child. Thanks to a sperm donor, they now have a lovely little girl.
I asked Siaran what she would say to anyone who was thinking of donating and she said, "I'd have to point at my daughter and say I'm just so incredibly grateful to whoever donated their sperm to help me have a child... when it can make that much difference, you just think that's got to be a fantastic thing to do."
Sperm donation literally gives the gift of life and as donor numbers have dried up, fewer and fewer people are receiving that gift.
So what has gone wrong? Well, the crisis seems to stem from the government's decision in 2005 to abolish the right of all sperm donors to remain anonymous. All men who registered as a donor after 1 April that year could have their identity revealed to the children created from their sperm when they turned 18.
The cliched image of the sperm donor has always been the medical student who filled a few pots in exchange for beer money. But what seemed like an easy way to help childless couples and earn some extra cash suddenly became less enticing at the prospect of up to 50 children (your sperm can be used by a maximum of 10 families) tracking you down and knocking on your door in the year 2023.
Unsurprisingly, a lot of men have been put off.
Clearly, something had to be done. So I undertook a mission to try to end the sperm crisis by not only raising awareness around the country, but actually asking men to come forward and donate as a pledge of support.
I decided to start with Labour MPs. After all, it was the government's change in the law that had led to this apparently disastrous shortage.
I made a list of MPs who fulfilled the donor criteria - male (that was crucial) and aged between 18 and 45. Armed with this, I headed to the Houses of Parliament in my mobile donation centre (a converted polling booth).
But, to my disappointment, the people who had stripped men of their right to anonymity were very keen to keep their own. I stood outside Parliament for hours trying to grab MPs to talk to, but no-one was willing to discuss sperm with me.
Undaunted, I booked a van and set off on a national sperm tour that would take in London, Oxford, Cardiff, Manchester, Newcastle, Carlisle, Edinburgh and Belfast. It was Belfast that shocked me most. The crisis is most acute here since, in the whole of Northern Ireland, there wasn't a single donor - not one.
Mechanics of donating
I went wherever men could be found - football matches, pubs, gay bars, fire stations, even a coalmine and a male voice choir. Everywhere I travelled, I was shocked by the confusion and lack of knowledge about donation and the law.
Some men thought that if they donated they would become financially responsible for the kids. One said: "So, what if they turn up aged 18 and make me buy them a Porsche?"
Danny shows off his mobile sperm donation centre
Others were worried about the mechanics of donation - one even thought he'd have to have sex with a woman who wasn't his wife - leading to understandable concerns.
Almost all the men were unaware of the need for donors.
But one thing is clear - it's not their fault that there is a crisis. A large number of those I spoke to were prepared to donate and genuinely wanted to help. One guy in Northern Ireland was so moved he decided to help - by becoming the first Northern Irish donor in decades.
"I put myself in their shoes," he said. "I thought what if I was that guy, what would I do? I don't want to be the one saying yeah, I'd love to have a sperm donor to help my wife have kids, but I'm not willing to give my sperm. It would be like if I needed blood but never thought about giving blood."
Other men were equally eager to give. The trouble was most of them wanted to do it anonymously.
The law was introduced to protect the rights of the unborn child and is supported by organisations such as Barnardos and the Children's Society.
Lack of funding
But with the drop in donor numbers I was keen to put some questions to the government: why, for example, they weren't organising a clear and focussed campaign to educate men about sperm donation.
The minister responsible, Caroline Flint, politely declined our requests for an interview, and her department issued us with a short statement:
SPERM DONOR FACTS
265 registered donors
Two-thirds of clinics getting 'no sperm' or having 'great difficulties'
Donor numbers peaked at 459 in the 1990s
SOURCE: HFEA and BBC
"Where UK clinics have focused on modernising their services to attract donors - for example, realistic clinic opening times, they are recruiting identifiable donors."
But my research found most clinics are simply too under-funded to run a successful campaign to recruit donors, or to extend their opening hours.
The government also claimed a recent rise in donor numbers. Indeed, the latest official figures do show an increase... of 15. Yes, 15 whole donors.
The small increase is thanks to recent media coverage of the issue. But it's what economists refer to as Dead Cat Theory: a slight rise in numbers doesn't necessarily indicate a return to glowing health - even a dead cat will bounce when you drop it.
What these figures don't reveal is that donor numbers dropped massively in the late 1990s. In 1995 there were 418 sperm donors in the UK. Today, it's 265. And only 208 of these donors are based here - more than a fifth of donors currently supplying UK clinics are overseas.
In a country of over 22 million men, only a measly 200 want to donate. Fertility experts estimate that we need 500-600 donors for the current demand to be met.
Now, who made me such an expert on this you might be asking. Well, I admit, I'm not a politician and I'm not a fertility expert - I'm just an ordinary bloke, but it's ordinary blokes like me and the blokes who read this and watch the programme I've made for the BBC who need to be convinced to part with their sperm if we are to solve this crisis. I suppose there's just one final question that I haven't answered: did I donate myself? Well, you'll have to watch the programme to find out.
Mischief: The Great Sperm Crisis is on BBC Three at 2100BST on Thursday 17 May
Below is a selection of your comments.
I attempted to become a sperm donor a couple of years ago, and found it near impossible to get information, and even more embarrassing when making enquiries as to how i go about it. If things were straight forward, I'd be happy to help out the cause, as I'm sure many other virile males also would.
I used to donate sperm in my late 20s. Wasn't for the money (£5 a go, then a bonus £20 every 10th time), but for the wanting "to give something back". I used to donate blood regularly and was on the database for bone marrow. I was horrified to see the change in laws about anonymity and with the way laws go in this country, was worried they could backdate it and thus I would become liable for child maintenance if the parents split up etc. I am sure there is some lawyer in this country who is just waiting for his claim to fame to challenge any laws which state this can't happen. But I still remember the security guard's face though when I used to drop off my sample before the clinic opened...
Mike, W. Sussex
As a former sperm donor I totally understand why numbers have dropped off. Predictably, the legislation was passed because a small but very vocal (and passionately sincere) group of campaigners lobbied MPs with great emotion, whilst a large but naturally discrete group of men maintained the very anonymity that was under threat... until it was gone. That is not good democracy. Whilst I sympathise with donor sperm children wanting to know their genetic parentage when they turn 18, the truth is our true parents are the ones who loved and cared for us out of choice for 18 years. I recommend reading Brecht's The Caucasian Chalk Circle for insight into this. In fact, the ironic truth is that most donor-sperm babies will never be told their origins since donors are matched as closely as possible with the father's physical characteristics. And so it should be.
Richard, London UK
I wouldn't have a second thought about donation if the anonymity existed. Whilst I understand that there isn't a financial requirement, and it's everything to do with health (which surely can be explored without finding out the identity of the donor), the idea that someone might turn up and claim that I'm their father and that they want to be part of my life is putting many men off. Blame the government.
Paul K, Birmingham
It's not so much the thought of "unwanted" 18-year-olds turning up at my doorstep that would put me off donating - in fact quite the opposite. I simply couldn't bear the thought that my offspring, my genes, effectively my children, may be out there somewhere, living lives I know nothing about. I would be worried sick about all the little me's.
Marcus, Hants UK
This story is a perfect example of politicians' talent of creating a problem where there is none. The need for anonymity for donors is real, and so is the need of the conceived children and their foster parents for much genetic and medical information about the donor; but technical means exist for supplying both of these needs. Politicians should be striving to support such solutions, instead of using the blunt instrument of wholesale legislation.
Amos Shapir, Kiryat Ono, Israel
I tried to donate at a clinic in Manchester but was told they did not need anymore donors at the moment - what's going on?
Jay Rawlinson, Manchester
Instead of helping families have a child through sperm donation, shouldn't we be encouraging them to adopt children who don't have a family?
Mike, Cambridge, UK
A donator now has to be either a very special or a very dumb person to risk both emotional and/or financial complications in their future life. The possibility of being "stalked" by one of your offspring, or overnight becoming financially responsible by some ill judged future European law, is not negligible. Indeed some donors WILL inevitably have problems and wish that they had never got involved. The law changed out of sensitivity for the children of donors but may have done more harm than good by reducing the broad range of men coming forward.
David Penn, Watford
At university a twice a week trip was a nice earner. Loads of us did it. But would never have done so without the cover of anonymity. This is yet another example of this government's complete lack of common sense.
I would be more than overjoyed to donate some of my essence in the knowledge that one day a son or daughter may introduce themselves to me. Being in a gay relationship, obviously we can't have children of our own, and feel that surrogating is needless, we would rather adopt a child that needs a home. However, the thought that I could help a childless couple fulfil their dream of having a baby, would be a rewarding one, but the need isn't really advertised is it - where do I go, how much do they want, am I offered tea and biscuits afterward? The law is a little confusing and I wouldn't know where to begin - the child has a right to know who their biological father is, but would I be financially viable for any part of their life? I would think not, and would hope that they were born into a family that really wanted them and appreciated the gift of life.
Carl Hunt, Exmouth, Devon
I think the issue of remaining anonymous is the single biggest issue that has ever held me back. It is such a chance to take. I don't think you can track down who gave you blood for instance, so why track down sperm donors? I have my own children to worry about instead of one knocking on my door in 18 years time.
Vaughan Jones, Nuneaton, UK
Rules can change and the CSA or its replacement might then consider the donor is liable for child support, since they can now get the information. While that might not be the case now, it probably could be in a few years time should family values rear its head in Westminster.
SJ West, Uxbridge
Wouldn't it have been helpful to inform those of us who are willing to donate the information we need so that we can?