Blood-thinning drugs such as aspirin could hold the key to treating a faulty gene that triggers miscarriages.
One in four pregnancies ends in a woman miscarrying and doctors now believe the problem may owe more to a genetic defect than to fertility complications.
Doctors at Care Fertility, a private provider of IVF treatment, have discovered that the gene can cause miscarriage in the mother even when it is present in the father.
The fault causes improper blood clotting and can be treated with blood thinners such as aspirin and heparin.
The gene, known as C4/M2, was present in 44 per cent of Care Fertility patients compared with just 15 per cent of the general population.
Professor Simon Fishel, the care body's managing director, said he believed it could be a major cause of recurrent miscarriage.
With proper treatment, he added, the number of couples having healthy babies increased to 38 per cent, a similar proportion to other infertility patients of the same age.
The findings were published in the journal Reproductive Biomedicine Online.
The genetic fault means the embryo is unlikely to implant in the womb or do so sufficiently, causing late miscarriage or growth problems in the baby.
If the woman is the carrier of the gene, she is also at risk of complications such as blood clots.
Professor Fishel said: "Very recently a new genetic marker has been found that predisposes couples to the risk of miscarriage, which we call the C4/M2 variant.
"In addition to the risk of implantation failure and miscarriage, it is linked to blood-clotting disorders, pre-eclampsia and low birth-weight babies.
"What I do find remarkable is that in the population of patients studied, the man has the same chance as the woman to pass on this variant to the developing embryo and disturb successful implantation. Where the genetic variant exists, the chance of delivering a baby is reduced to one in four that of fertile couples."
Care Fertility intends to screen patients for the faulty gene so they can be treated appropriately.
A spokesman for the Miscarriage Association said: "We always welcome new research into factors that can increase the risk of miscarriage, so we'll be looking closely at these findings with the help of our research expert advisers."