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BookmarkScienceDaily (Nov. 8, 2008) — High blood pressure experienced during pregnancy could be a woman's earliest warning that she is at risk of developing heart disease - the number one killer of Canadian women - says Queen's University professor of Obstetrics and Gynecology, Graeme Smith.
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Called pre-eclampsia, this type of high blood pressure occurs in 5-10 per cent of all pregnancies.
But because most practicing physicians are unaware of the connection between pre-eclampsia and the risk for future cardiovascular problems, they fail to follow up with screening tests. As a result, their patients aren't taking proactive steps to avoid potential heart attacks and strokes.
According to the 2007 Heart and Stroke Foundation Annual Report on Canadians' Health, Canadian women have now caught up to men in cardiovascular deaths, with almost 37,000 deaths annually from heart disease and stroke.
"This should be on every obstetrician's and family doctor's radar screen," says Dr. Smith, an expert in high-risk obstetrics who is affiliated with Kingston General Hospital's Perinatal Research Unit. "What's exciting for our research team is that we're mostly dealing with young, healthy women who now have the opportunity to protect themselves from developing a life-threatening condition years down the road."
The study, which began five years ago, has followed the progress of 400 Ontario women, half of whom developed pre-eclampsia during their pregnancy. When screened a year after delivery, the women with pre-eclampsia showed underlying cardiovascular risk factors of elevated blood pressure and lipids (fats) at a rate that was two to three times greater than the control group.
The researchers don't think that pre-eclampsia causes these symptoms, however. "They probably pre-dated pregnancy and were the background upon which pre-eclampsia developed," says Dr. Smith, who heads a multi-university research team studying pre-eclampsia. Instead, he suggests that pre-eclampsia is the earliest marker of potential future cardiovascular risk.
In a recent study showing that the incidence of hypertension (high blood pressure) in Ontario women of reproductive age is the same as the incidence of pre-eclampsia - about seven per cent - the researchers conducting the survey failed to ask women about their pregnancies. "The awareness isn't there yet," says Dr. Smith, suggesting that guidelines be established for longer-term follow-up.
Noting that pregnancy is a type of stress test for people who are already in the health care system, he adds: "It can reflect underlying problems that may be reduced by changes in lifestyle before medication is required."
Dr. Smith is leader of the Canadian Institutes of Health Research (CIHR) and Heart & Stroke Foundation Pre-Eclampsia New Emerging Team (PE-NET).
The findings are published online in the American Journal of Obstetrics and Gynecology.
Other members contributing to the paper are: Melissa Swansburg, Heather Ramshaw and Michelle Roddy (from Queen's Department of Obstetrics and Gynecology); Mark Walker, Shi Wu Wen and Ruth Rennicks White (University of Ottawa); Michelle Hladunewich (U of T) and Aizhong Liu (Central South University, China).
