Abstract
Background
Systolic hypertension has emerged as a predictor of maternal morbidity, with current guidelines recommending treatment of systolic blood pressure ≥160 mmHg regardless of diastolic values. However, evidence supporting the independent prognostic significance of elevated systolic pressure in pregnancy remains limited, as most historical data emphasized diastolic thresholds.
Objective
To evaluate whether isolated severe systolic hypertension, defined as systolic blood pressure ≥160 mmHg with diastolic pressure <110 mmHg, was associated with a composite of adverse maternal outcomes.
Study Design
This was a secondary analysis of the multicenter Assessment of Perinatal Excellence cohort, which included 115,502 patients from 2008 to 2011 at 25 hospitals participating in the Eunice Kennedy Shriver National Institute of Child Health and Human Development Maternal-Fetal Medicine Units Network. Peak blood pressure values were obtained at any time between hospital admission for delivery and discharge, with elevated blood pressure defined by at least 2 readings taken 30 minutes or more apart. Those with a systolic blood pressure ≥140 mmHg and/or diastolic blood pressure between 90 and 109 mmHg during delivery admission were included. Normotensive patients and those with a diastolic blood pressure of ≥110 mmHg were excluded. Patients with mild hypertension (systolic blood pressure 140–159 mmHg and/or diastolic blood pressure 90–109 mmHg) comprised the reference group; the study groups included those with isolated severe systolic hypertension (≥160 mmHg), further subdivided into 2 groups based on the peak systolic blood pressure. The primary outcome was a composite of adverse outcomes documented during delivery admission, including hypertensive stroke, pulmonary edema, elevated creatinine (≥1.5 mg/dL), disseminated intravascular coagulation, cardiopulmonary arrest, and death. Multivariable models adjusted for maternal age, body mass index, chronic hypertension, diabetes, preterm birth, and cesarean delivery.
Results
Of the entire cohort, the reference group included 32,277 patients (27.9%) with mild hypertension, while 3790 (3.3%) had systolic blood pressure 160 to 179, and 2178 (1.9%) had systolic blood pressure ≥180 mmHg. Following adjustment for possible confounders, patients with peak systolic blood pressure of 160 to 179 had an almost 3-fold increase (adjusted relative risk, 2.8; 95% confidence interval, 2.1–3.6) in the rate of the composite adverse outcome, and those with 180 and more had an almost 4-fold increase (adjusted relative risk, 3.8; 95% confidence interval, 2.9–5.1), driven primarily by pulmonary edema and elevated creatinine. Further cohort stratification by smaller intervals of the peak systolic blood pressure showed a linear trend with the composite adverse outcome. Patients with isolated severe systolic hypertension were also more likely to be associated with intensive care unit admission, eclampsia, hemolysis, elevated liver enzymes, and low platelet syndrome.
Conclusion
Severe hypertension diagnosed solely by systolic blood pressure (diastolic <110 mmHg) had a stepwise association with the composite adverse outcome when compared to mild hypertension, driven primarily by pulmonary edema and elevated creatinine. Interpretation is limited by the lack of treatment data and inability to determine the temporal relationship between blood pressure measurements and outcomes. These findings add to the growing evidence base recognizing the prognostic significance of systolic hypertension in pregnancy.