The number of American women with chronic high blood pressure who are dying during and after pregnancy is up sharply, a new study warns.
Of 155 million births in the United States between 1979 and 2018, more than 3,200 mothers died of high blood pressure-related causes— a 15-fold rise over the period. The risk was particularly high among Black women, according to the study.
“Women need good and timely initiation of prenatal care during pregnancy, but importantly, preconception care to diagnose and treat increased blood pressure prior to pregnancy is very important,” said lead author Cande Ananth, chief of epidemiology and biostatistics at Rutgers Robert Wood Johnson Medical School in New Brunswick, N.J.
“Monitoring blood pressure frequently and monitoring diet and body weight are targets worthy of consideration,” he said.
While maternal death rates due to high blood pressure during pregnancy (preeclampsia) fell in the United States over the last four decades, death rates from chronic high blood pressure substantially increased — on average, by about 9% a year, according to the study.
“There is also a disconcerting race disparity in these unfavorable trends…, with Black women at substantially and disproportionately increased risk than white women,” he said. “The study underscores the need for focusing improvements in such areas as advanced maternal age, obesity and racial inequities in access to care.”
About a third of maternal deaths occur before delivery; a third on the day of delivery or within a week; and a third one week to a year after delivery, according to the study.
The leading cause of pregnancy-related deaths was heart and blood vessel disease, including high blood pressure disorders, researchers found.
They estimated that 75% of the maternal deaths were preventable.
Notably, those linked to high blood pressure increased with age and were highest among women between 45 and 49. Deaths also increased with obesity.
Among Black women, the risk was even higher.
Compared with white women, they had three to four times the risk of dying from blood pressure-related causes, the study found. And, Ananth said, that racial disparity has persisted for 40 years.
Although preeclampsia treatment has improved, treatment of chronic high blood pressure hasn’t, he said, possibly because many women go undiagnosed. Another factor: The best way to treat high blood pressure early in pregnancy isn’t clear.
Lifestyle changes may make a big difference, Ananth said. This includes quitting smoking and drinking, eating a healthy diet and maintaining a healthy weight before and during pregnancy.
According to the study, about 8 in 10 women with preeclampsia see their blood pressure return to normal after pregnancy. But high blood pressure persists for life in about 20%, Ananth said.
Dr. Erin Michos, associate director of preventive cardiology at Johns Hopkins University School of Medicine in Baltimore, reviewed the findings.
She said doctors are doing a better job of identifying and treating new cases of high blood pressure that emerge during pregnancy, but this study shows that they are not doing as well addressing chronic high blood pressure.
“It is really chronic hypertension that is driving maternal deaths now,” she said. “I think doctors are doing a better job paying attention to preeclampsia, but not so much high blood pressure in younger women before they get pregnant.”
The good news: Chronic high blood pressure can be prevented, Michos said. Major risk factors are increasing age and obesity — and, she said, obesity is preventable.
“But unfortunately, obesity levels are at an all-time high in the U.S. population, with the lifestyle factors of an unhealthy diet, decreased physical activity and sedentary behavior being major contributors,” Michos said, adding that psychological stress and social factors such as access to care are also factors.
“Other data have shown that the cardiovascular health of pregnant women and women of reproductive age in the U.S. has worsened over time,” she said.
That maternal death rates were four times higher among Black women than white women is “unacceptable,” Michos said, and the need for public health attention to that gap is urgent.
“This racial disparity is likely due to social inequities, reduced access to care and other disparate treatment that can stem from systemic racism,” she said.
The best strategy, Michos suggested, is to improve heart health before pregnancy through weight management and a blood pressure check. She also urged women to “know their numbers” — a normal blood pressure is less than 120/80 mmHg.
“While we may not treat blood pressure with drug therapy until it is much higher, everyone benefits from a healthy lifestyle,” she said.
Weight loss or weight maintenance, stepping up physical activity, reducing salt intake, increasing consumption of potassium-rich foods and minimizing alcohol use can all help, Michos said.
The new study was published recently in the journal Hypertension.
For more about high blood pressure, visit the American Heart Association.
SOURCES: Cande Ananth, PhD, MPH, chief, epidemiology and biostatistics, Rutgers Robert Wood Johnson Medical School, New Brunswick, N.J.; Erin Michos, MD, MHS, associate director, preventive cardiology, Johns Hopkins University School of Medicine and director, Women’s Cardiovascular Health, Johns Hopkins Ciccarone Center for the Prevention of Cardiovascular Disease, Baltimore; Hypertension, December 2021