Nicola and Nigel Dawson's dreams of parenthood were realised when they conceived using donated eggs and sperm – but they had to go to Spain to do it. Alice-Azania Jarvis explains why

Last month, Nicola and Nigel Dawson played host to a rowdy collection of friends, family, and babies. The party gathered to attend the naming ceremony, and celebrate the first birthday, of the Dawsons' twin daughters, Mia and Hannah. Like virtually every parent on their child's first birthday, Nicola and Nigel were brimming with pride. "We still look at them every day and can't believe it. They mean the world to us."

Of course, in the Dawson's case, there is particular reason to feel lucky. The twins are theirs, but not biologically. Mia and Hannah were both conceived, after several gruelling attempts at IVF, with the eggs and sperm of strangers – donors whose identity they will never know, since the treatment took place in Spain, where donor anonymity is preserved.

Nicola met Nigel nine years ago, when she was 26 and he 32. "On our first date we were talking about kids, says Nicola. "It was pretty obvious that he was the one." Two years later, they were married and started trying for a child immediately. After another year, with still no baby on the way, they went to see their GP. Nigel has a very low sperm count, though initially that went undetected. "Their words were that he had a "very respectable" sperm count. I went to a gynaecologist, who found I had abnormalities in my hormone levels."

By October 2004, the Dawsons had embarked on their first cycle of IVF, which, since they didn't qualify for free treatment within their Primary Care Trust, wasn't cheap. Three failed IVF cycles and £15,000 later, they discovered that Nicola may be experiencing an early menopause, and was unlikely to conceive at all.

The choice they faced was adoption or conception using donor eggs. At first adoption seemed like the obvious solution. "After three IVF cycles we felt drained," explains Nicola. But before long, they realised it wasn't the option for them. So instead, they decided to try donor treatment.

The problem was availability. The UK currently suffers from an exceptional shortage of donors. Between 2004 and 2006 the number of treatment cycles using donated eggs fell 25 per cent, while the numbers using donated sperm fell by 30 per cent. There are currently only around 800 registered egg donors in the UK – and the number of sperm donors, at around 300, is even lower. As a result, UK patients face hefty waiting lists and relatively low success rates.

"We were told by our clinic that we would have to wait 18 months to two years for treatment, but when we looked at overseas treatment, the waiting period was only 4-6 weeks." What's more, the clinics offered success rate of 60 per cent, 20 per cent higher than had been quoted in the UK.

Faced with the statistics, Nicola and Nigel decided to travel to Barcelona for treatment. In doing so, they joined growing numbers of Britons heading abroad for fertility treatment. The most popular destinations are Spain and the Czech Republic, where eggs are plentiful and donors, as well as being able to preserve their anonymity, receive reasonable financial "compensation" for their efforts. While in the UK donors' expenses are capped at £250, in the Czech republic women can claim up to €500 (£460) and, in Spain, €900. The discrepancy has prompted some, including Professor Lisa Jardine of the Human Fertilisation and Embryology Authority to call for a regulatory review.

Once in Spain, Nicola and Nigel were given an English-speaking administrator to deal with all of their concerns, "She was our constant point of contact. We never felt we were bothering her. Our doctor was wonderful. She spoke fluent English. They were all very clear, very impressive people."

Along the way, there was one blow: the doctors discovered further issues with Nigel's sperm count. Nicola and Nigel were advised to use donor sperm. "It was a bit upsetting at first – the thought that they wouldn't be genetically related to either of us. But that was temporary. If we'd adopted, it would have been the same. so we found it very easy to get our heads around it."

At £8,000, the treatment wasn't cheap – but it didn't take long to take effect. Five weeks after approaching the clinic, doctors had found a genetic match. Nicola and Nigel returned to Barcelona for treatment, which proved successful. "We were overjoyed," enthuses Nicola. "I took about 11 pregnancy tests before I went and had the proper test." The rest of their care, from the scans to the birth, was received in the UK.

A year on, Nicola and Nigel are as enchanted with Mia and Hannah as they have been from day one. "From the very first photo – of two embryos, healthy, eight-cell embryos – we've said 'They are ours'.'"

They have chosen not to hide the fact that they aren't their daughters' biological parents, and have started telling the girls already. Nevertheless, at the clinic staff had gone out of their way to ensure a genetic similarity between donors and prospective parents. "They said that nobody should ever be able to tell that they're not ours. Mia looks like me and Hannah like Nigel, though they have these amazing brown eyes and olive skin. I don't mind – they're going to be gorgeous!"

To Nicola and Nigel, the fact that their children won't know the identity of their biological parents is a negative – primarily because of the lack of health history they will have – though there's little doubt that Spain's laws on donors' anonymity are one reason for their relative plenty. Since 2005, children born from sperm and eggs donated in the UK have been able to discover the identities of their biological parents; the effect has been a catastrophic decline in donor numbers.

More than that, however, Nicola sees our relative ignorance of the issues surrounding donorship as the primary culprit in explaining the UK's shortfall. "I don't think people realise the amazing difference they can make to people's lives. They obviously have concerns over what will become of their genetic offspring – but if you get as far along the process as we did, you're not going to take parenting lightly."

It's an opinion shared by the UK's biggest infertility support group, the Infertility Network, who see working towards public debate on donorship as the way to achieve progress. "There's a huge education process to be had," says the network's Susan Seenan. "We need more people to at least come forward and find information. And when they do, we need to have the resources to support them."

Another issue to be addressed, says Susan, is that of payment. While there are plenty of reasons to be sceptical of paying vast amounts, there seems little doubt that, at very least, a more adequate compensation system needs to be encouraged. "At the moment the same compensation is offered for sperm and eggs, but the process is very different."

In the meantime, the number of couples in need of donors looks likely only to rise, and with it the flow of patients to the Continent. And while the UK's situation is in clear need of reform, the fact that the option of "fertility tourism" exists is no bad thing. "At the moment, it's a welcome option," agrees Susan. "The next step is to provide a real choice for couples: do they want to stay in the UK or do they want to go abroad? But at least the European alternative exists."

Making babies: The egg and sperm shortage

* In April 2005, the Government lifted anonymity for egg and sperm donors. Now anyone born by donated sperm, eggs or embryos can obtain identifying information about the donor when they reach the age of 18.

* The decision has widely been blamed for a increased shortage in sperm donations. Although the number of donors is slowly on the increase, the figure of 284 in 2008 is still much lower than the high of 417 recorded in 1996, and demand (approximately 4,000 patients per year) far outstrips supply.

* The result is lengthening waiting lists and a growing number of "fertility tourists" seeking treatment outside the UK – Spain and the Czech Republic being the most popular destinations. Spain offers anonymity and also pays both egg and sperm donors.

* The number of egg donors has increased from 783 in 2006 to 1,084 in 2008. This may be due to "egg-sharing", where women are offered free IVF treatment in return for donating spare eggs.

* There is a much greater shortage of eggs than sperm, as sperm donors may donate to up to 10 families, where egg donors will donate to only one.

* Professor Lisa Jardine, chair of the Human Fertility and Embryology Authority, has called for a debate on whether people should be paid for donating eggs and sperm. Charlie Minter