Miscarriage is heartbreaking and its causes often mysterious. Clare Rudebeck meets the doctor whose pioneering clinic offers couples hope for the future

When Professor Lesley Regan was training to be a doctor, she was frequently called to see women who had just had a miscarriage. "One particular night, I remember seeing a couple who had just lost their child. They were distraught, asking me why it had happened," she remembers. "I didn't know and the text books couldn't tell me. They would say it was 'nature's way' and that nothing could be done. I looked at this couple and thought, 'This isn't good enough.'"

Prof Regan is now the head of the largest miscarriage referral unit in the world at St Mary's Hospital in London. The clinic treats 1,000 women every year. Each of these women will have had at least three miscarriages when she begins attending the clinic. And yet the success rate is impressive: 80 per cent of them will go on to have a baby.

Without the help of Prof Regan's clinic, the prospect for those who have had multiple miscarriages is bleak. Losing one baby is common – at least one in six pregnancies end in a miscarriage. But only one in 100 women will have three consecutive miscarriages and, at that point, their chances of having a fourth would normally be 43 per cent. Little is known about what causes them to lose their babies and little specialist help is on offer. A survey by the Miscarriage Association found that 45 per cent of women who miscarried did not feel well informed about what was happening.

When Julie Orton, 39, arrived at the clinic, she had already had three miscarriages and was losing hope of having a live birth. "I just felt like a murderer," she says. "It wasn't deliberate, of course, but it's still your body that's doing it. I kept thinking I was doing something wrong. Was that bath too hot? Did I exercise too much or too little? The only thing I was hoping for when I arrived at the clinic was a diagnosis – a reason why it was happening."

As part of preliminary tests, the clinic found that she was in fact pregnant again. Julie, who works for a home-loans company in East Grinstead, had little confidence that this pregnancy would be full term. Seven weeks later she lost her fourth baby.

The clinic carried out full tests to try to discover why her babies were not surviving. Like 15 per cent of the women referred to the clinic, she was found to have the autoimmune disorder, antiphospholipid antibodies (APA). APA affects the blood supply to the placenta, starving the foetus of oxygen. The clinic has found that by treating these women with a daily aspirin and injections of the anticoagulant, heparin, the chances of a live birth are increased from 10 per cent to 70 per cent.

The diagnosis gave Julie and her partner Rui the confidence to try again. "It was the first time in my life that I wanted something to be wrong with me," she says. "It was a big relief, and I know I wouldn't have tried again without a diagnosis. I don't think I could have coped with it. I certainly know Rui couldn't have."

Like Julie and Rui, many couples want an explanation for their miscarriages. But many cannot be given one. Prof Regan estimates she is currently only able to diagnose 20 to 25 per cent of her patients with an underlying medical reason for their failed pregnancies. The main reason is that many miscarriages really are caused by sheer bad luck. Being unlucky means conceiving a foetus that is chromosomally abnormal. The baby would have no chance of survival, and is therefore aborted by the body. It is very common, can happen to anyone and is untreatable.

But miscarriage remains very under-researched and Prof Regan's clinic is leading the field in discovering the underlying medical explanations for serial miscarriages. As well as researching the effects of APA, they have found that uterine and vaginal infections can be a cause, especially of late miscarriage. Chlamydia is one such cause, which is treated with antibiotics. Twenty per cent of the women who miscarry late have the vaginal infection bacterial vaginosis (BV). Little is known about BV, but it is also treatable with antibiotics.

Another possible reason is a weak cervix, which causes the cervical canal to open too early. In this case, a stitch is inserted to help keep it closed. Prof Regan is researching the lining of the womb, looking at which cells are needed when the fertilised egg is implanted to have a successful pregnancy.

But she stresses that women should not despair if an underlying reason cannot be found for their miscarriages. "Couples often want there to be a problem, because they think that problem equals treatment equals a cure," she says. "In fact, their chances are often better if we can't find a problem. They may just have been unlucky with their first three pregnancies."

So if many miscarriages are, and will remain, untreatable, how does she account for her remarkable success rate? "Tender loving care in early pregnancy is very beneficial," she says. "If a woman is well looked after by highly trained professionals, she will do better."

Julie Orton had a weekly scan and a fortnightly consultation with a specialist throughout her pregnancy. "There was a lot of psychological help at the clinic," she says. "Just to have somebody telling you everything was fine made a big difference. Because of their expertise, you feel very safe in their hands."

Prof Regan works very hard to maintain the standard of the service she provides, and the clinic also provides an optional counselling service for couples. "Many of my patients have travelled hundreds of miles to see us," she says. "They deserve a really good second opinion. I do my utmost to make sure they are seen by a specialist in the area."

It was this reassurance that helped Julie believe she would be able to have a child. "I still wake up every day and think, 'Are you alive in there?" she says. "Up until 12 weeks into the pregnancy, I was very worried. Every time I had a scan, I'd be OK for a few days and then I'd start to worry again. I was pleased they allowed me to come back every week, because I don't think I could have coped with every fortnight."

Prof Regan is determinedly optimistic about women's chances of a live birth, even after multiple miscarriages. "We never say goodbye to anybody at the clinic," she says. "This morning I delivered a baby whose mother had previously had seven losses."

Luckily for Julie Orton, it didn't take that long. She is due to give birth to her first child any day now, her fifth pregnancy. "I'm getting fed up with moving around," she says. "But I've waited three years for this, so I can wait a bit longer."

During the last four weeks she and Rui have had the confidence to discuss names. "Over the last few weeks, I've actually started to think that I am going to have a baby," she says. "I've felt very positive since they told me that even if it came out early, it would be viable. We made sure the nursery was ready by 36 weeks in case it was premature. But in fact, it doesn't look like it will be early, I think it's going to be late!"

'Staying Alive: Tales of Miscarriage' will be shown at 9pm tomorrow on Channel 4