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Canadian researchers have developed a cheap, easy method of screening pregnant women for placental damage -- the leading cause of stillbirth, premature birth and dangerously high blood pressure in mothers-to-be.

In fact, the tests that can provide advance warning of these potentially serious problems to both mother and baby are largely done already, but need to be interpreted differently.

Researchers stressed, however, that screening for placental damage should be restricted to high-risk moms -- those who have already had problematic pregnancies.

"We're not there yet for new moms," said John Kingdom, an obstetrician in the division of maternal-fetal medicine at Mount Sinai Hospital in Toronto and the senior researcher.

"But these tests can provide a lot of reassurance for high-risk moms."

The research, published in today's edition of the American Journal of Obstetrics & Gynecology, shows that a series of three simple tests, conducted between 16 and 23 weeks gestation, can identify, fairly accurately, whether the placenta is formed and functioning properly.

If it is not, a number of measures can be taken to improve pregnancy outcomes.

The tests include: maternal serum screening: a blood test used to identify Down syndrome; uterine artery Doppler imaging: a test that checks maternal blood flow in the placenta (the Doppler is already done to check for heart abnormalities); ultrasound of placental morphology: a test done to check the shape of the placenta (again, ultrasounds are already done to check the size of the fetus).

Dr. Kingdom noted that none of the tests are invasive, and only slight variations are required to check specifically for placental damage.

"Technically, placental screening is no more difficult and no new equipment and no new staff is required to do this screening," he said.

The study involved 212 women treated at the Mount Sinai placenta clinic over a four-year period. All of them were at high risk because of earlier pregnancy problems such as stillbirth or pre-eclampsia (very high blood pressure in pregnancy), because they have medical conditions such as diabetes, or because they conceived using in vitro fertilization.

Among those with normal test results, the risk of pre-eclampsia was 80 per cent lower, the risk of premature birth was 90 per cent lower and the risk of having an extremely low-weight baby who was unlikely to live (a condition known as early onset intrauterine growth restriction or IUGR) was 95 per cent lower than among the women with abnormal test results.

The pregnant women who have abnormal test results can be treated with a number of measures, including blood thinners such as heparin, and being scheduled for cesarean sections.

Tanya McLaurin of Ottawa said she wishes this kind of screening and treatment had been available to her. She lost two babies, Spirit at 23 weeks, and Angel at 27 weeks, because of placental damage.

"The placenta wasn't properly attached so nutrients weren't flowing to the baby," Ms. McLaurin explained.

During both pregnancies, she suffered from pre-eclampsia, which also put her life at risk.

Ms. McLaurin was told about the risks of Down syndrome during her pregnancy, but doctors never mentioned placental damage, which is far more common and more devastating to the baby.

"The frustration for me is that the knowledge was out there, but I wasn't told about it," she said. "I tell my story so other women won't have to go through the experience I did, losing two little ones."

Dr. Kingdom said he shares that frustration. He noted that as many as one in 50 women suffer some placental damage.

Dr. Kingdom said placental damage is also becoming far more common because the condition is associated with older mothers, in vitro fertilization, obesity and diabetes, all of which are on the rise.

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