One pregnancy in seven ends in miscarriage during the first three months, but researchers say that if very early or unrecognised losses are taken into account, the real miscarriage rate may be as high as 60 per cent.
About five per cent of women have two or more losses, while recurrent miscarriage - defined in the UK as three or more consecutive miscarriages - affects around one in 100 couples trying for a baby.
In most cases of recurrent miscarriage, no cause is found, despite couples being tested for anatomical, hormonal, clotting, genetic and other risk factors.
But research at the Biomedical Research Unit at Warwick suggests that a major cause, especially of recurrent pregnancy loss, is defects in the way a womb prepares for pregnancy - a process called decidualisation.
It involves multiple changes in the lining of the womb, including changes in supporting cells, and blood vessel and glandular development.
Decidualisation makes the womb lining receptive to implantation to allow an early embryo to attach to and so support early pregnancy.
The research also showed that during decidualisation, the cells that line the womb gain the ability to detect good- and poor-quality embryos, so acting as 'quality control' for pregnancy. It is believed these so-called stromal cells do not function properly in women who suffer recurrent miscarriage.
Treatment for the condition proved elusive, until Israeli researchers discovered that injuring the womb lining resulted in improved fertility in women undergoing IVF.
They found that women who had undergone a uterine biopsy, in which a pipelle is used to scrape away some of the womb lining in order for it to be tested, had almost twice the rate of pregnancies and births as a control group.
Now a trial is under way at Warwick University with 100 women with a history of two or more miscarriages. Half will have the surface of their womb scratched and the remainder will have a placebo procedure.
The pipelle is inserted into the womb and then rotated through 360 degrees to achieve a scratching effect.
'The procedure involves an internal examination similar to a standard cervical smear test,' said Prof Quenby. 'The tube is gently moved inside the womb for ten seconds so that all surfaces are scratched.
"The tube is withdrawn and contains some womb lining tissue which can be used for research."
One theory is that the injury, like any wound, triggers an inflammatory response, resulting in production of growth factors and other chemicals which in turn promote decidualisation.
Another part of the repair of any injury is to attract and activate stem cells which have the ability to both rapidly grow and change into other cells.
Stem cells in the lining of the womb are important in decidualisation and lacking in women with repeated miscarriages.
Samantha Gallacher, 33, has had two miscarriages and is taking part in the trial.
She says: 'The first miscarriage occurred at four weeks, and the second at ten.
"After the second, I was admitted to hospital and luckily there was a member of the research team there who told me about the trial. I had the treatment or a placebo - I do not know which - and we are now waiting to see what happens."
