Abstract 049: De Novo Postpartum Hypertension In A Safety-net Hospital: Incidence And Risk Factors

Abstract

Introduction: Postpartum hypertension can be persistent, following a pregnancy complicated by hypertension, or new onset ( de novo ), following a normotensive pregnancy. The postpartum period is traditionally defined as six weeks after delivery, yet accruing evidence shows that hypertension underlies the majority of severe maternal morbidity events through a year postpartum. While guidelines for enhanced monitoring of women at risk of persistent postpartum hypertension exist, less is known about risk factors for de novo postpartum hypertension. The aim of this study is to estimate the incidence of and identify risk factors for de novo postpartum hypertension among a diverse safety-net hospital population through the entire year postpartum. Hypothesis: We assessed the hypothesis that women with de novo postpartum hypertension share similar demographic and reproductive characteristics to women at increased risk of cardiovascular related maternal morbidity. Methods: We conducted a cohort study of 8,531 deliveries at Boston Medical Center from 2016-2018. Data on demographics, reproductive history, and labor and delivery were obtained from medical records. All documented blood pressure measures from pregnancy through 12 months postpartum were extracted. Women with chronic hypertension or hypertensive disorders of pregnancy were excluded. De novo postpartum hypertension was defined as two separate blood pressure readings with systolic blood pressure (SBP) ≥ 140 mmHg and/or diastolic blood pressure (DBP) ≥90 mmHg at least 48 hours after delivery. Severe de novo hypertension was defined using criteria of SBP ≥160 and/or DPB ≥110. We examined the distribution of demographic and pregnancy characteristics among women with and without de novo postpartum hypertension. Secondary analyses restricting to women with healthcare visits after six weeks postpartum were also conducted. Results: Among the 6,631 women without a history of hypertension, 10% (n=660) developed de novo postpartum hypertension; a third of whom had severe hypertension (n=225). Compared to women without de novo hypertension; cases were more likely to be non-Hispanic Black; delivered via cesearean section; have had a preterm delivery; and be multiparous. In analyses restricted to women with visits extending past six weeks postpartum (n=3,272), the incidence of de novo postpartum hypertension was 16.6%. Approximately 30% of these cases were diagnosed after the traditionally used six week period. Conclusion: In conclusion, 1 in 10 women with normotensive pregnancies experience de novo hypertension in the year after delivery, with a third of these cases developing after six weeks. Opportunities to monitor and manage women at the highest risk of de novo hypertension throughout the entire year postpartum could mitigate cardiovascular related maternal morbidity.