Kristy Herd pictured with her five week old daughter Hayley who was born prematurely after Kristy developed Preeclampsia for case study on an Australian team discovering for the first time the cause of the condition...taken at Nepean hospitalsmh newsphotos Ben RushtonTuesday May 8 2012

''A traumatic condition'' ... Kristy Herd, with five-week-old daughter Hayley, had pre-eclampsia - which can kill mother and child - in all three of her pregnancies. Photo: Ben Rushton

A leading cause of maternal death, pre-eclampsia usually affects only first-time mothers. But Kristy Herd has endured the traumatic condition, where the mother's immune system rejects the foetus, in all three of her pregnancies.

Mrs Herd's five-week-old daughter Hayley is in the neonatal unit of Nepean Hospital following her birth. The Werrington mum also suffered from pre-eclampsia when she was expecting son Declan, who's now a healthy eight-year-old, and daughter Breana, who died from brain cancer at 14 months.

This finding would be particularly important for women in regional areas, who may not be close to hospitals that can deal with complicated births 

"[Pre-eclampsia] is a really traumatic condition," Mrs Herd said. "With Hayley, I woke up with some pain in my belly at 29 weeks, went in to hospital, and about 40 minutes later I was getting an emergency C-section. My partner wasn't there with me, my placenta ruptured, I lost a lot of blood and ended up in intensive care. 

"I think I'm only just starting to get over it all."

Pre-eclampsia affects up to 10,000 Australian women each year, and can be fatal to mother and child. It can lead to cerebral palsy, vision and learning problems in the child, and seizures or coma in the mother.

The symptoms include swelling and high blood pressure, and the only remedy for the disease is to deliver the baby, usually prematurely.

But now there's hope for detecting the condition before its symptoms even appear.

A study by a team from the University of Sydney, published in this month's Journal of Reproductive Immunology, found that the thymus - an organ of the immune system which sits behind the breastbone - was "significantly" smaller in foetuses whose mothers went on to develop pre-eclampsia.

The senior author of the study, Ralph Nanan, said doctors have no way to predict who will get the condition, though first pregnancies and obesity are risk factors.

"We think pre-eclampsia is an immune disease, as the mother's immune system rejects the foetus for unknown reasons," said Professor Nanan, from Sydney Medical School Nepean.

"So it's quite exciting to find that the thymus, the central immune organ of the foetus, is much smaller in pre-eclampsia children than children from healthy pregnancies. But we don't know yet what causes the thymus to be smaller in some children."

The study looked at 53 pregnancies with pre-eclampsia and 120 healthy pregnancies, measuring foetal thymus size between 17 and 21 weeks gestation.

Prof Nanan hopes further studies will allow doctors to preempt the disease. "This would be particularly important for women in regional areas who may not be close to hospitals that can deal with complicated births," he said. "Doctors could put a high-risk management plan in place from an earlier stage of pregnancy."

The researchers are now conducting a prospective study of 1200 pregnant women to strengthen the findings and hope to develop a test for pre-eclampsia. They will also look at the relationship between the developing thymus and immune diseases and allergies.