Study Emphasizes Need for Long-Term Monitoring of Hypertension After Childbirth

A new study finds that 1 in 10 women who did not have hypertension prior to or during pregnancy may develop the condition up to 1 year after giving birth. The study, published in Hypertension, noted that women with no history of high blood pressure may develop hypertension in the weeks that follow childbirth; however, data are lacking on the development of hypertension more than 6 weeks following delivery, according to the study.

The development of postpartum hypertension can lead to conditions such as stroke, cardiovascular disease, and kidney failure later in life. However, existing research efforts into this area underestimates the burden of new-onset postpartum hypertension, according to the study investigators.

“The study findings have implications for postpartum care, particularly among patients without a history of hypertension,” lead author Samantha Parker, PhD, assistant professor of epidemiology at Boston University School of Public Health, said in a press release.

The study authors examined medical records for demographic characteristics and prenatal, delivery, and postpartum data from 3925 pregnant people who gave birth between 2016 and 2018 at the Boston Medical Center. The investigators evaluated blood pressure measurements taken in the prenatal period through 12 months post delivery, which were taken at the hospital during office visits, urgent and emergency care visits, and readmissions.

New-onset postpartum hypertension was defined as at least 2 separate blood pressure readings taken 48 hours after delivery with a systolic blood pressure of at least 140 mmHg and a diastolic blood pressure of least 90 mmHg. Cases deemed as severe blood pressure included systolic readings of at least 160 mmHg and diastolic readings of at least 110 mmHg.

The study found that 43% of the study population received a first-time hypertension diagnosis post hospitalization, with approximately half of these new cases occurring more than 6 weeks postpartum. This finding emphasizes the need for blood pressure monitoring during the entire postpartum period, according to the investigators.

The study also found that nearly one-quarter of hypertension cases developed 6 weeks or more post childbirth. The data showed that the 3 greatest risk factors for post-delivery hypertension were being over 35 years of age, current or former smoking, or having delivered a baby via Cesarean section.

Prior research on postpartum hypertension largely focused on blood pressure measurements recorded during delivery or hospital readmissions, according to the current study. Additionally, standard postpartum care includes just a single clinical visit within 4 to 6 weeks post delivery, which means that many new hypertension cases that developed 6 weeks to 1 year after childbirth may be undiagnosed, according to the study.

The researchers included a racially and ethnically diverse group of participants in the analysis. They found that patients with any of the 3 greatest risk factors had a 29% risk of developing postpartum hypertension, which increased to 36% in non-Hispanic Black patients.

The study authors said their findings may help to improve understanding of the persistent racial disparities in US maternal morbidity and mortality, and how hypertension may contribute to these disparities.

“Understanding this relationship between pregnancy and hypertension is particularly important in addressing inequities in maternal cardiovascular disease and death for people of color,” Parker said in the release.

Further, the results emphasize the need to develop strategies that identify and manage postpartum high blood pressure among high-risk populations prior to discharge from the hospital after childbirth, according to the study authors.

“We were surprised at the number of cases captured more than 6 weeks after delivery, a period that falls well outside of routine postpartum follow-up,” Parker said in the release. “Monitoring during this period could mitigate severe postpartum and long-term cardiovascular complications.”

Reference

Parker, S.E. et al. (2022) De novo postpartum hypertension: Incidence and risk factors at a safety-net hospital, Hypertension. Available at https://www.ahajournals.org/doi/10.1161/HYPERTENSIONAHA.122.19275. Accessed December 6, 2022.