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Protecting pregnant women's hearts

Having a baby can raise your risk of heart disease. Researcher Margie Davenport wants to reduce that risk
Dr. Margie Davenport

Pregnancy complications can increase a woman’s risk of heart disease for the rest of her life. That’s why Dr. Margie Davenport’s research is targeting ways to prevent common but serious complications like pre-eclampsia from happening in the first place. 

Pre-eclampsia is marked by a sudden onset of high blood pressure during pregnancy. It disappears once the baby is delivered. Yet the risk to a woman’s heart health never goes away, says Dr. Davenport, an exercise physiologist and assistant professor at the University of Alberta. 

Research shows that a woman who develops pre-eclampsia is at double the risk of developing heart disease later in life, compared to women who did not have pre-eclampsia.

In 2011, the American Heart Association identified pre-eclampsia and other pregnancy complications, including gestational hypertension and diabetes, as risk factors as strong as smoking

It was a significant change in the way researchers looked at pregnancy and heart disease, says Dr. Davenport. 

That roughly 8% of women develop preeclampsia is a sobering statistic, Dr. Davenport says, especially when you consider the 30-year survival rate for women who develop pre-eclampsia before 34 weeks gestation. 

That means if a 26-year-old develops complications before the 34th week of her pregnancy, the likelihood that she’ll be alive at age 56 drops to 86%. “That’s substantial,” Dr. Davenport stresses. “Typically, in a woman who was otherwise healthy, we'd expect that number to be 99 or 100% at 56 years of age.” 

Healthy women at risk 

Most cases of pre-eclampsia show up in women who would otherwise be considered healthy. The risk is higher in first pregnancies, and in older women. Heart disease and stroke risk factors like unhealthy weight and diabetes also put women at risk.  

It’s still unclear what causes pre-eclampsia. 

One theory is that the sympathetic nervous system that controls the body’s fight or flight response is overactive in some women. The physical stress of pregnancy could also play a role. 

“Pregnancy is a big stress test,” says Dr. Davenport, a recipient of a Heart & Stroke New Investigator Award in Women’s Cardiovascular Health. In addition to growing the baby, she points out, a woman is growing a placenta — a whole new organ — plus her blood volume increases 50% and her hormone levels skyrocket. 

“It's a very significant cardiovascular and physiological stress. Even just a small little problem that you would never know about suddenly becomes apparent when you add the extra stress of pregnancy.”  

Exercise could protect women  

Although there is no cure for pre-eclampsia, the solution, Dr. Davenport believes, may lie in exercise.  

Physical activity is proven to reduce heart disease in women who aren’t pregnant. 

”We actually know very little about the cardiovascular implications of exercise during pregnancy,” Dr Davenport says.

As part of her research, Dr. Davenport has reviewed data from multiple studies to better understand if women who exercise while pregnant reduce their risk of developing pre-eclampsia. Her findings, along with any recommendations about the frequency, intensity and type of exercises that could be prescribed to pregnant women to reduce their risk, will be published in the Canadian Clinical Practice Guidelines for Exercise and Pregnancy in 2018. 

Research is still ongoing, Dr. Davenport cautions. But she urges women who are concerned about their risk factors, or who want to begin an exercise program while pregnant, to talks to their doctors.  

Meanwhile she is focused on the research goal: “We hope to provide women clear direction that will help them have a safe pregnancy today and reduce their risk of heart disease tomorrow.”