More Women Face Long-Term Risks Of Hypertensive Disorders During Pregnancy

Per-pregnancy rates of hypertensive disorders may underestimate the number of women at risk for these conditions, whereas per-woman rates might give a better sense of the scope of the problem, a study suggests.

Analyzing data on 7,544 local women who had 9,862 pregnancies between 1976 and 1982, researchers at the Mayo Clinic in Rochester, Minnesota, found that 719 of the women had hypertensive disorders while pregnant, making the per-pregnancy incidence 7.3%.

Then, in a subset of the cohort, the researchers calculated the per-woman rate of pregnancy-related hypertension. Among 1,839 women with 4,322 pregnancies, 281 women, or 15.3%, had these conditions - more than double the percentage that was calculated per pregnancy.

"Over the last 20 years, it has been increasingly recognized that hypertensive disorders of pregnancy (HDP) are linked to elevated risks for cardiovascular disease (CVD) later in life," said lead study author Dr. Vesna Garovic of the Mayo Clinic.

But the number of women at risk for cardiovascular disease later in life based on their pregnancy histories was underestimated, as the incidence of HDP, and its most severe form preeclampsia, were commonly expressed per-pregnancy, Dr. Garovic said by email.

"We demonstrate that the incidence of HDP and preeclampsia more than doubled when assessing on a per-woman basis, when taking into account all of her pregnancies," Garovic said. "Consequently 1 in 6 women may be at risk for CVD based on their pregnancy histories."

Researchers looked at four categories of hypertensive disorders of pregnancy: preeclampsia, gestational hypertension, chronic hypertension and superimposed preeclampsia. They reviewed each woman's medical chart to determine which women had possible HDP, where a positive screen was defined as two elevated blood pressures taken at any prenatal visit, during delivery, or postnatal before hospital discharge.

During a follow-up period of 36.2 years, 571 women with a history of HDP went on to develop a variety of chronic health problems at higher rates than women without any history of HDP, researchers report in the Journal of the American College of Cardiology.

For example, women with HDP were more than twice as likely to develop congestive heart failure and hypertension, with adjusted hazard ratios of 2.11 and 2.31, respectively. Women with HDP were also more likely to develop cardiac arrhythmias (HR 1.33), coronary artery disease (HR 1.59), stroke (HR 1.76), chronic kidney disease (HR 1.75), dementia (HR 1.86), and diabetes (HR 1.62).

One limitation of the study is that the population was predominantly white. Another is that the pregnancies occurred decades ago.

"Women of color, particularly black women, have increased rates of hypertensive disorders of pregnancy and also have increased rates of heart and kidney disease," said Dr. Michael Honigberg, co-author of an editorial accompanying the study and a clinical and research fellow in cardiology at Massachusetts General Hospital and Harvard Medical School in Boston.

"Future studies are needed to understand these relationships in diverse racial and ethnic groups," Dr. Honiberg said by email.

"For women who have a history of hypertension in pregnancy, it is very important that these women share this history with their primary care provider," Dr. Honiberg said. "History of HDP provides an opportunity for women to incorporate heart-healthy diet and lifestyle modification early to prevent or at least delay the development of heart disease risk factors."

—Lisa Rapaport

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