Pregnancy Events Reveal Cardiovascular Risk

Some Complications Signal Seven-fold Increase in Risk of Heart Disease Death

Oakland, CA (Sept. 21, 2015) — Women who experience complications during pregnancy may be at greater risk of dying from heart disease later in life than women with uncomplicated pregnancies, according to new research from the Public Health Institute published today in the American Heart Association’s journal Circulation.

Researchers found that some combinations of pregnancy complications were associated with as much as a seven-fold increase in risk of cardiovascular disease death overall. Other complications were associated with a four- to five-fold higher risk of dying of cardiovascular disease early, before the age of 60.

“Pregnancy is really a stress test for the cardiovascular system,” said senior study author Barbara A. Cohn, PhD, of the Public Health Institute’s Child Health and Development Studies (CHDS) in Berkeley, CA. “And it can be used to identify women at highest risk for cardiovascular disease death so they can receive earlier and more intensive preventive care.”

This large, longitudinal study, which followed women for half a century, confirmed several pregnancy complications associated with cardiovascular disease reported in other studies (pre-eclampsia, pre-term delivery and small-for-gestational-age delivery) but also uncovered new risks, finding that cardiovascular death risk increased significantly for combinations of some pregnancy events. It also found that pre-eclampsia in early pregnancy strongly predicts premature death from cardiovascular disease.

Cardiovascular disease death risk increased:

•  7.1 times when a woman had pre-existing high blood pressure (diagnosed up to 20 weeks of pregnancy) and a pre-term delivery
• 5.6 times when a woman had pre-existing high blood pressure and pre-eclampsia
• 4.8 times when a woman had pre-existing high blood pressure and small-for-gestational-age delivery

Researchers also found that a woman’s risk of dying early, before age 60, from cardiovascular disease increased 5 times when she had gestational high blood pressure combined with a preterm delivery, and 3.7 times when she had pre-eclampsia accompanied by delivery of a small-for-gestational-age infant.

In addition, they identified two new pregnancy complications that predispose women to heart disease death:

• Risk of cardiovascular disease death increased 4.2 times when a woman had glycosuria, or high levels of sugar in the urine
• Risk of cardiovascular disease death increased 1.7 times when a woman had hemoglobin decline, a measure of the red blood cells’ ability to carry oxygen

The researchers also reported an unexpected result: high blood pressure that developed after 20 weeks of pregnancy was associated with cardiovascular disease death only in African-American women. This difference by race/ethnicity was statistically significant.

African-Americans, who made up 22 percent of the study population, were 1.7 times more likely to die of cardiovascular disease, while Asian, Caucasian and Hispanic women had no statistically significant increased risk due to gestational hypertension.

Researchers analyzed data from 15,528 pregnant women in the Oakland, CA, metropolitan area who were enrolled in CHDS from 1959 to 1967. Surveillance of this study cohort has continued for more than five decades, and the participants are now well into the age of cardiovascular disease risk.

Thirty-one percent of women in the study had a single pregnancy complication (4,293) and five percent had two or more (710). As of 2011, 368 women (average age 66) in the cohort had died of cardiovascular disease.

Cardiovascular disease is the No. 1 killer of American women. According to the American Heart Association, 399,503 women died of cardiovascular disease in 2013.

“Taking a comprehensive pregnancy history is a low-cost intervention that can make the incredible advances in cardiovascular disease medicine accessible to higher risk women of all ages,” Cohn said. “These risk factors should lead doctors to discuss with these women ways to reduce their risk of heart attack and other cardiovascular diseases.

“By asking women about pregnancy history, doctors might be able to save lives.”

View the manuscript online after September 21, 2015.