Friday, July 30, 1999 Published at 00:43 GMT 01:43 UK
Miscarriage prevention therapy 'does not work'
Doctors do not know why some women are prone to miscarriage
Immune system therapy given to women who suffer more than one miscarriage could be a waste of time, research suggests.
In fact the study, published in The Lancet medical journal, found women having the treatment had more miscarriages compared to those getting none.
This, combined with other evidence which points at the risk of serious side effects, means few doctors are likely to recommend it in future.
Miscarriage is the most common complication affecting pregnancy, and recurrent miscarriages affect between half and one per cent of couples.
One theory suggests it is the mother's own immune response which reacts negatively to the father's genetic material in the foetus.
Some women are now given treatment involving white blood cells from the father to de-sensitise their immune system and allow pregnancies to continue unhindered.
The method has always been controversial, with trials providing conflicting information on its success.
This latest study, at centres in the US and Canada, was the first large trial randomly comparing those given treatment and those left alone.
A pregnancy carried to over the 28-week mark - at which stage most babies survive birth- was judged a success.
All of the 180 women involved had suffered at least three miscarriages - half were immunised with paternal white cells, and half given a placebo treatment of salt water.
The researchers found only 46% of the pregnant women given active treatment avoided miscarriage, as opposed to 65% in the no-treatment group.
They concluded: "This therapy should not be offered as a treatment for pregnancy loss."
Serious side effects
A spokesman for the National Childbirth Trust said the method had been linked with hepatitis infection, anaphylactic shock and even infertility in older women.
She said: "It was very popular at one time, and seemed to be the answer to everything.
"But the evidence of risks from side effects is increasing, and I don't believe that many people are using it now."