Independent, The (London): Come with me to the IVF clinic and I'll show you how easy it is to

Black babies born to a white mother? A huge shock to the parents and a national scandal, but no surprise to those of us who have been through IVF treatment on the NHS. We could see that one coming. "There is very little chance of you having a baby here," a consultant at the local hospital told my wife and me. His fertility unit had just enough money to keep going but not enough to make women pregnant. The ultrasound clinic was always overbooked or closed, so scans were taken days after it was too late, and there was nobody to read them because the one full- time nurse was on maternity leave. We could go on trying to get treatment, he said, but there was little point. "Unless, of course, you have any money."

As Mrs A, birth mother to the black twins, has found, it is risky trusting your fertility to the NHS. Overworked people in underfunded units make mistakes - although exactly what went wrong in this case, and the consequences, will be the subject of a court hearing in October.

The basic point, however, is that all IVF couples, even those who can find pounds 3,000 a time to pay for it, play an extraordinary game of roulette. And most do it with their eyes closed. We always joked about our baby looking South Korean, because the consultant who eventually supervised our IVF was. The truth behind this rather lame joke is that, once sperm and egg are taken into the laboratory, the process is out of our hands. The wonderful, mysterious act of conception that would normally take place in the fires of passion, in the hidden crucible of a womb, is entrusted to an embryologist in a green coat and surgical cap.

Neither partner really knows what goes on in the lab, and most of us don't care. Why? Let's put it in context: by the time she was implanted, my wife had gone through several invasive operations, five years of failed drug treatments, hormone therapies that changed her mood, weight and appearance, a thousand battles with the hospital system, and countless cycles of hope and despair. We had also paid a small fortune. Mr and Mrs A were lucky to get their treatment on the NHS, although it won't seem like that to them now.

Every year, 27,000 couples have fertility treatment. Each woman who goes in for IVF knows she has only a 15 per cent chance of pregnancy, and few believe it is going to work. The only hope is to trust that the doctors know better. So, you think, who cares what happens in the lab? Let them perform their secret magic, as long as there's a baby at the end of it.

Come with me to the clinic and I'll show you why we should care. There's the wannabe mum lying on a bed under a light general anaesthetic, having her eggs taken out and rushed away. Meanwhile, here am I in a private cubicle, trying to concentrate so as not to have to open the tatty green folder full of old porn mags. Everything we hope for depends on my ability to produce a good sample. Right here, right now. Very sexy. Afterwards I write my name on the pot and hand it over, feeling improbably like a man. But what if I forget, in my embarrassment? What if the nurse sees the mistake after I have gone, and writes down the wrong name? The wrong egg will receive my seed. If the mother is white like me, will she ever know?

There is nothing for either partner to do after giving up the ingredients but go home and try to forget what's going on at the clinic, where there are cabinets full of microscopic life cooking away. A few years ago a hospital mislaid dozens of embryos. Let's hope that doesn't happen again. The first time a black baby was born to a white woman by IVF, in December 1993 in the Netherlands, the cause was a basic hygiene error: the pipette used to introduce Willem Stuart's sperm to his wife's eggs had not been cleaned properly. It still contained sperm from another man. The result: twins, one white, one black.

In a day or so our phone rings with news that some of the eggs have become embryos, and their cells are dividing nicely. We are allowed to go in and look down a microscope at life pulsating in a petri dish. Cells don't have their father's noses, or their mother's name tattooed on non-existent foreheads, so how do we know they are anything to do with us? The doctor says so; it must be true.

Then it's time for my wife to put on a gown, rest on a bed, and take her place in the queue. There are perhaps a dozen women waiting to receive embryos, and a dozen dishes lined up for them. Each should have a name written on the base and lid. But what if a lid gets put on the wrong dish and nobody notices? Four years ago, a woman in New York gave birth to black and white twins after being mistakenly implanted with an embryo created for a different couple. Suppose one of the other women waiting at our clinic doesn't turn up, or the running order is confused? If you're having Gift, a treatment requiring general anaesthetic so the embryos can be inserted by laproscope, the patient is unconscious and unable to confirm her name. What if the nurses are stressed and don't check? These things happen. It is the job of the Human Fertilisation and Embryology Authority to make sure the safeguards are there, but levels of funding are not far off what they were when it was formed 10 years ago. Clinics with good reputations might not get inspected for two or three years.

Dr Sammy Lee of the Portland Hospital in London admits that the lab can be "a very stressful environment. If you have got a lot of couples coming through, the incubator is full of dishes, and you are working to a very tight schedule, then it is possible that the wrong dish may have been taken out of the incubator".

Nobody knows how many embryos have ended up in the wrong wombs. And I'm not sure how many of those who are getting ready for treatment as you read this will care enough to be put off. My wife and I got lucky, twice, and had babies thanks to IVF, but I have also seen friends spend tens of thousands of pounds and break up with their partners under the pressures of treatment. No evidence of medical incompetence, however dramatic, will make them give up while there is any hope of a child.

Since 1978, more than 300,000 women in the world have conceived by IVF and today one child in every 80 in Britain is an IVF baby

The Human Fertilisation and Embryology Authority regulates, licenses and collects data on fertility treatments and has devised a code of practice

About 44,000 IVF treatments are carried out in Britain each year compared with 28,000 10 years ago. Almost 80 per cent of IVF is carried out privately.