De Novo Postpartum Hypertension: Incidence and Risk Factors at a Safety-Net Hospital

BACKGROUND: Postpartum hypertension can be persistent, following a pregnancy complicated by hypertension, or new onset (de novo), following a normotensive pregnancy. The aim of this study is to estimate the incidence and identify risk factors for de novo postpartum hypertension (dn-PPHTN) among a diverse safety-net hospital population. METHODS: We conducted a retrospective cohort study of 3925 deliveries from 2016 to 2018. All blood pressure (BP) measures during pregnancy through 12 months postpartum were extracted from medical records. Patients with chronic hypertension or hypertensive disorders of pregnancy were excluded. dn-PPHTN was defined as 2 separate BP readings with systolic BP ≥140 mm Hg and diastolic BP ≥90 mm Hg at least 48 hours after delivery. Severe dn-PPHTN was defined as systolic BP ≥160 and diastolic BP ≥110. We examined risk factors individually and in combination and timing of diagnosis. RESULTS: Among the 2465 patients without a history of hypertension, 12.1% (n=298) developed dn-PPHTN; 17.1% of whom had severe dn-PPHTN (n=51). Compared to those without dn-PPHTN; cases were more likely to be ≥35 years, delivered via cesarean, or be current or former smokers. Patients with all of these characteristics had a 29% risk of developing dn-PPHTN, which was elevated among non-Hispanic Black patients (36%). Approximately 22% of cases were diagnosed after 6 weeks postpartum. CONCLUSIONS: More than 1 in 10 patients with normotensive pregnancies experience dn-PPHTN in the year after delivery. Opportunities to monitor and manage patients at the highest risk of dn-PPHTN throughout the entire year postpartum could mitigate cardiovascular related maternal morbidity.