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Background: Hypertensive diseases of pregnancy are associated with severe maternal morbidity and remain common causes of maternal death. Recently, national guidelines have become available to aid in recognition and management of hypertension in pregnancy to reduce morbidity and mortality. The increased morbidity related to hypertensive disorders of pregnancy is presumed to be associated with the development of severe hypertension. However, there are few data on specific treatment or severe maternal morbidity in women with acute severe intrapartum hypertension as opposed to severe preeclampsia.

Objective: The study aimed to characterize maternal morbidity associated with women with acute severe intrapartum hypertension, and to determine whether there was an association between various first-line antihypertensive agents and posttreatment blood pressure.

Study Design: This retrospective cohort study of women delivering between July 2012 and August 2014 at 15 hospitals participating in the California Maternal Quality Care Collaborative compared women with severe intrapartum hypertension (systolic blood pressure >160 mm Hg or diastolic blood pressure >105 mm Hg) to women without severe hypertension. Hospital Patient Discharge Data and State of California Birth Certificate Data were used. Severe maternal morbidity using the Centers for Disease Control and Prevention criteria based on International Classification of Diseases-9 codes was compared between groups. The efficacy of different antihypertensive medications in meeting the 1-hour posttreatment goal was determined. Statistical methods included distribution appropriate univariate analyses and multivariate logistic regression.

Results: There were 2252 women with acute severe intrapartum hypertension and 93,650 women without severe hypertension. Severe maternal morbidity was significantly more frequent in the women with severe hypertension (8.8%) compared to the control women (2.3%) (P < .0001). Severe maternal morbidity rates did not increase with increasing severity of blood pressures (P = .90 for systolic and .42 for diastolic). There was no difference in severe maternal morbidity between women treated (8.6%) and women not treated (9.5%) (P = .56). Antihypertensive treatment rates were significantly higher in hospitals with a level IV neonatal intensive care unit (85.8%) compared to a level III neonatal intensive care unit (80.2%) (P < .001), and in higher-volume hospitals (84.5%) compared to lower-volume hospitals (69.1%) (P < .001). Severe maternal morbidity rates among severely hypertensive women were significantly higher in hospitals with level III neonatal intensive care unit level compared to hospitals with a level IV neonatal intensive care unit (10.6% vs 5.7%, respectively; P < .001), and significantly higher in low-delivery volume hospitals compared to high-delivery volume hospitals (15.5% vs 7.6%, respectively; P < .001). Only 53% of women treated with oral labetalol as first-line medication met the posttreatment goal of nonsevere hypertension, significantly less than those treated with intravenous hydralazine, intravenous labetalol, or oral nifedipine (68%, 71%, and 82%, respectively) (P = .001). Severe intrapartum hypertension remained untreated in 17% of women.

Conclusion: Women with acute severe intrapartum hypertension had a significantly higher risk of severe maternal morbidity compared to women without severe hypertension. Significantly lower antihypertensive treatment rates and higher severe maternal morbidity rates were seen in lower-delivery volume hospitals.