CHICAGO — Women who develop hypertension during pregnancy face a substantially increased risk of cardiovascular events later in life, based on a review of more than 4,000 women.
Hypertension in pregnancy is an “underrecognized risk factor” for subsequent cardiovascular events and for developing other markers of elevated cardiovascular risk, Dr. Vesna D. Garovic said at the annual scientific sessions of the American Heart Association.
“Traditionally, hypertension in pregnancy was not thought to play a major role in cardiovascular disease,” noted Dr. Garovic, a nephrologist at the Mayo Clinic in Rochester, Minn. But based on these findings, physicians who care for middle-aged or elderly women should obtain a history of their pregnancy outcomes. Women with a history of hypertension in pregnancy need aggressive treatment to reduce their modifiable risk factors, and close monitoring for the onset of cardiovascular events, she said.
Results from prior studies of women who had hypertension in pregnancy did not establish these links, probably because they involved relatively few women and had relatively brief follow-up. Those studies also lacked racial and ethic diversity, and often focused exclusively on cardiovascular death as their end point.
Dr. Garovic and her associates analyzed comprehensive clinical information gathered for women in the Family Blood Pressure Program, a study organized and funded by the National Heart, Lung, and Blood Institute. The study group of nearly 4,800 women included roughly equal numbers who were white, African American, Hispanic, and Japanese. The group included 3,421 women who were normotensive during each pregnancy, 643 women who developed hypertension during at least one pregnancy, and 718 women who had no pregnancy that lasted longer than 6 months. (This third group was not included in the analysis.)
The key index event was hypertension in pregnancy and not preeclampsia because the researchers who ran the Family Blood Pressure Program collected data only on hypertension during pregnancy and not information on the incidence of proteinuria or edema during pregnancy.
The women's median age was 54 years when their clinical data were collected, and cardiovascular events were only counted if they first occurred after age 39.
The cumulative incidence of stroke among the women who had hypertension in pregnancy was 5.2%, compared with 2.7% among those who were normotensive in pregnancy, a statistically significant difference. The rate of coronary heart disease was 6.8% among those with a history of hypertension during pregnancy, compared with 5.4% among those without this background, also a statistically significant difference.
The prevalence rates of several risk factors for cardiovascular disease were significantly greater in the women with a history of hypertension in pregnancy compared with those who had no such history, even after controlling for possible confounding factors. (See table.)
The prevalence of hypertension at the time of data collection was 61% among women with a history of hypertension in pregnancy, compared with 57% among those without this history. More notably, the average age of hypertension onset was 52 years for the women who had hypertension in pregnancy, compared with 60 years for those who did not.
Women who develop hypertension in pregnancy may have underlying endothelial dysfunction. Pregnancy may serve as a physiologic “stress test” that transiently unmasks the condition, and the disorder and its consequences become more overt again later in life. Alternatively, in some predisposed women, pregnancy itself may trigger endothelial dysfunction that later leads to other disorders, Dr. Garovic said.
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