Timely treatment of severe hypertension and risk of severe maternal morbidity at an urban hospital

Abstract

Hypertensive disorders of pregnancy have been identified as a leading contributor to severe maternal morbidity and mortality. Pregnant persons with hypertensive disorders who develop severe hypertension at delivery admission have been shown to experience higher rates of severe maternal morbidity relative to those without severe hypertension. Current guidelines recommend prompt treatment of severe hypertension given known associated maternal and fetal risks; however, only 1 previous study has described an association between timeliness of antihypertensive therapy and risk of severe maternal morbidity. This study aimed to characterize how development of severe intrapartum hypertension and its timely treatment affect the risk of severe maternal morbidity. We conducted a population cohort study of deliveries with and without hypertensive disorders of pregnancy at a single urban hospital between 2016 and 2018. Among deliveries of persons with hypertensive disorders of pregnancy, we identified those with persistent severe hypertension (defined as blood pressure ≥160/105 mm Hg sustained over ≥15 minutes) and further classified individuals with severe hypertension as having received timely (within 60 minutes) or delayed treatment. Severe maternal morbidity was identified using a composite measure developed by the Centers for Disease Control and Prevention. We calculated overall and indicator-specific rates of severe maternal morbidity for 4 categories of deliveries: without hypertensive disorder of pregnancy, with hypertensive disorder of pregnancy without severe hypertension, with severe hypertension and timely treatment, and with severe hypertension and delayed treatment. We assessed the association between hypertensive disorder of pregnancy, severe hypertension, timeliness of treatment, and severe maternal morbidity using multivariable robust Poisson regression, adjusting for demographic and clinical characteristics. Of 3723 delivery hospitalizations within the study time frame, 32.3% (1204/3723) were complicated by presence of a hypertensive disorder without severe hypertension and 5.7% (211/3723) by presence of a hypertensive disorder with severe hypertension. Among those with severe hypertension, 48.8% (103/211) received timely treatment. Compared with deliveries not complicated by a hypertensive disorder, severe maternal morbidity risk was increased for hypertensive disorder of pregnancy without severe hypertension (124.4/1000 vs 52.0/1000; adjusted risk ratio, 1.84; 95% confidence interval, 1.41-2.40), severe hypertension with timely treatment (233.0/1000; adjusted risk ratio, 3.81; 95% confidence interval, 2.45-5.92), and severe hypertension with delayed treatment (305.6/1000; adjusted risk ratio, 5.38; 95% confidence interval, 3.75-7.73). Patients with hypertensive disorders of pregnancy are at an elevated risk of severe maternal morbidity, and development of severe hypertension further increases this risk. Timely antihypertensive treatment is associated with lower risk of severe maternal morbidity among those with severe hypertension. These findings emphasize the importance of provider education and quality improvement efforts aimed at expediting treatment of severe hypertension.