Prevalence of Hypertension in the Late Postpartum Period by Hypertensive Status in Pregnancy

To better characterize how blood pressure (BP) abnormalities in pregnancy inform the risk of late postpartum hypertension by describing rates of hypertension and associated patient attributes in the late postpartum period (6 weeks-6 months) by hypertensive status during pregnancy.

This retrospective cohort study included all patients delivering within an academic health care system between 2012 and 2023. All BPs from fertilization to 6 months postpartum were obtained from the electronic medical record. Elevations in BP of two or more systolic BPs of 140 mm Hg or higher or two or more diastolic BPs of 90 mm Hg of higher were used to assign patients to one of four categories: normal BPs throughout pregnancy and delivery, elevated BPs only before 20 weeks of gestation, elevated BPs from 20 weeks through delivery hospitalization discharge, or elevated BPs throughout pregnancy. Next, BPs from late postpartum (6 weeks-6 months) were categorized per American College of Cardiology (ACC)/American Heart Association (AHA 2017 guidelines as normotensive, elevated, stage 1, or stage 2. The association of pregnancy BP status and patient clinical and demographic characteristics with the distribution of ACC/AHA stages in the late postpartum was assessed with χ² tests or Kruskal-Wallis tests as appropriate. Crude and adjusted multinomial regression analyses were performed.

Of the final population of 31,751 patients, 58.6% had normal BPs, 0.9% had elevated BPs only before 20 weeks of gestation, 35.5% had elevated BPs only at or after 20 weeks, and 5.0% had elevated BPs throughout pregnancy and delivery. Late postpartum, 60.8% were normotensive, 15.6% were elevated, 18.9% were stage 1, and 4.7% were stage 2. Patients with elevated BPs throughout pregnancy were significantly more likely to develop stage 2 hypertension late postpartum compared with those who were normotensive in pregnancy (adjusted odds ratio 23.14, 95% CI, 18.15-29.49).

Nearly 40% of patients have elevated BPs in the late postpartum period, and those with elevated BPs throughout pregnancy are at highest risk of meeting criteria for stage 1 or 2 hypertension. Review of specific BPs in pregnancy may be a valuable screening tool in identifying patients at risk of BP abnormalities late postpartum.