In an analysis of more than 2,400 women, regarding 1 in 10 without a history of blood pressure problems were diagnosed with high blood pressure within a year of giving birth, according to a research article published today in Hypertension, a journal of the American Heart Association. Almost a quarter of women were diagnosed more than six weeks following giving birth – a time when many women stopped receiving follow-up care.
“The results of our study have implications for postpartum care, especially in women without a history of high blood pressure,” said study lead author Samantha Parker, Ph.D., assistant professor. of epidemiology at the Boston University School of Public Health. “We were surprised at the number of cases captured more than six weeks postpartum, a period that falls well outside routine postpartum follow-up. Monitoring during this period might mitigate serious postpartum and long-term cardiovascular complications.”
High blood pressure following childbirth, called postpartum hypertension, is usually discovered within six weeks of giving birth, either immediately following delivery or during a woman’s last postpartum clinic visit. , 4 to 6 weeks following delivery. Data are limited beyond 6 weeks, as most studies have relied on blood pressure measurements during childbirth or hospitalization, which include only the first postpartum days and capture only the the most serious cases.
In severe cases, postpartum hypertension is associated with life-threatening complications including stroke, heart failure, kidney failure, etc. And, while it is well established that women with hypertension before or during pregnancy are at risk for cardiovascular disease later in life, very few studies have assessed cardiovascular risk in women who develop hypertension. for the first time or a new appearance. hypertension following childbirth.
“Learning more regarding high blood pressure beyond 6 weeks postpartum can provide insight into alarming racial disparities in maternal health,” Parker said. “Previous research has shown that new-onset hypertension following childbirth may be up to 2.5 times more common in non-Hispanic black women than in white women.”
The study aimed to estimate the frequency of new-onset postpartum hypertension in a racially diverse population. The researchers also wanted to determine contributing factors so healthcare professionals might identify pregnant patients at risk. The researchers evaluated the medical records of 8,374 deliveries with a gestational age of at least 20 weeks from 2016 to 2018 at Boston Medical Center, a large safety-net central urban hospital in Boston. Hospitals with a safety net tend to have a higher percentage of patients with low family income, and they are more likely to have no health insurance or rely on Medicaid for health care coverage.
The researchers assessed the risk of high blood pressure among the 2,465 women in the group who had no history of pregnancy-related high blood pressure or a history of chronic high blood pressure. Participants were 18 years and older, 54% identified as non-Hispanic black, 18% as Hispanic or Latino, and all had received prenatal care and delivered at the same hospital. Demographic and reproductive characteristics from medical records were reviewed along with weight and pre-existing conditions, such as type 2 or gestational diabetes.
For the study, new-onset postpartum hypertension was defined as systolic blood pressure (the upper number of a blood pressure measurement) of 140 mm Hg or greater and/or diastolic blood pressure (the lower number) 90 mm Hg or more. . Severe hypertension was defined as systolic blood pressure of 160 mm Hg or higher and/or diastolic blood pressure of 110 mm Hg or higher. Blood pressure measurements were taken at least 48 hours following delivery, and additional blood pressure measurements were obtained from hospital records during the first year following delivery. Most patients (91%) had at least one clinical visit following delivery during which their blood pressure was measured.
The analysis looked at risk factors individually and in combination, as well as the time of diagnosis of hypertension. Data analysis revealed:
- 298 women (12.1%) with no history of arterial hypertension developed hypertension in the year following childbirth.
- Most diagnoses of postpartum hypertension occurred soon following delivery, but 22% of cases were diagnosed more than six weeks following delivery.
- Risk factors for recent-onset postpartum hypertension included women aged 35 or older, having had a cesarean section, or being a current or former cigarette smoker.
- Women with all three risk factors had a 29% risk of developing new postpartum high blood pressure, and the risk was elevated at 36% in women who also identified as non-Hispanic black.
The study notes that determining best care practices for a racially and ethnically diverse population first requires a systematic approach to identifying women with new-onset postpartum hypertension.
The researchers add that future research should aim to understand adverse effects associated with postpartum hypertension, such as hospital readmissions, later pregnancy complications, and cardiovascular disease. “Additionally, understanding the relationship between pregnancy and hypertension is particularly important in addressing inequalities in maternal cardiovascular disease and death among people of color,” Dr. Parker said.
Limitations of the study include that it was a single center study and that the results are not necessarily generalizable to other regions or to pregnant women under 18 years of age. Additionally, the data came from electronic medical records from standard office visits, meaning there was not a protocol for proactively collecting blood pressure measurements for analysis; for this reason, factors such as inconsistency in the timing and frequency of measurements may have resulted in variability in the analysis. Additionally, blood pressure measurements in the clinic may not reflect the “true” average blood pressure: some people have much higher or lower blood pressure measurements during office visits that may not reflect their blood pressure. blood pressure under normal conditions.
The co-authors are Ayodele Ajayi, MBBS, MPH; and Christina Yarrington, MD
Funding for the study was provided by the Early Career Catalyst Pilot Award from the Boston University School of Public Health and a grant from the National Heart, Lung, and Blood Institute, a division of the National Institutes of Health.
