Page last updated at 17:08 GMT, Sunday, 27 July 2008 18:08 UK

Immune clue to pregnancy danger

Pregnant woman
Pre-eclampsia can put mothers and babies at risk

The body's own immune system may cause pre-eclampsia, a common condition which is potentially dangerous for pregnant women and their babies.

Pre-eclampsia affects one in 20 pregnancies, but experiments on mice in the US found that it could be triggered by immune molecules.

This could potentially help lead to new treatments and tests for the condition, reports the journal Nature Medicine.

A pre-eclampsia charity said other evidence hinted at the immune link.

The possibility that it is auto-immune is supported by other, curious evidence, that women with many sexual partners have a higher risk of pre-eclampsia
Dr Margaret Macdonald
Action on Pre-eclampsia

It is hard to predict which women will be affected by pre-eclampsia, although those with a family history of the condition, or who have had it in previous pregnancies, are at greater risk.

It generally starts after the 20th week of pregnancy, and warning signs can include high blood pressure and protein in the urine.

However, it is not easily treated, and if it worsens, it can place the health of both mother and unborn baby at risk. Often, the only solution is to deliver the baby, even prematurely.

The causes are not understood, but scientists at the University of Texas believe the response of the mother's immune system to the pregnancy may hold the key.

To test this, they took immune molecules called "autoantibodies" from women with pre-eclampsia and injected them into mice.

The mice started to develop a condition very similar to pre-eclampsia in humans - they had high blood pressure, protein in the urine, and telltale abnormalities in the placenta, the organ grown by the mother to supply the foetus with oxygen and nutrients.

When the Texan team also gave mice a drug which blocked the action of these autoantibodies, this condition did not develop, supporting the theory that they played a part in the disease.

They suggested that as well as revealing something about the cause of the disease, it might point to potential tests and treatments.

Drug danger

However, Professor James Walker, consultant obstetrician at St James's University Hospital in Leeds and spokesman for the Royal College of Obstetricians and Gynaecologists, said he would need further evidence to be convinced that these molecules were the direct cause of the condition in humans.

He said: "It's very interesting research, and there is other research suggesting that the immune system is involved in pre-eclampsia, but we don't know how much this is the cause of the condition, and how much is an adaptation by the mother to counter its effects.

"Unfortunately, you can't just give the drug they used here in pregnant women, as about a third of the babies will die."

Dr Margaret Macdonald, the chief executive of the charity Action on Pre-eclampsia, said there had been very little progress in half a century of research into the causes of the condition.

"The possibility that it is auto-immune is supported by other, curious evidence, that women with many sexual partners have a higher risk of pre-eclampsia than women with few, long-term partners," she said.

"This suggests immune stimulation by 'foreign material' might be involved."

Test 'to predict pre-eclampsia'
13 Feb 08 |  Health

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