Hypertensive disorders include preeclampsia, gestational hypertension, and chronic hypertension and complicate up to 10 percent of pregnancies. As a group, they are one member of the deadly triad—along with hemorrhage and infection—that contributes greatly to maternal morbidity (Judy, 2019).
Preeclampsia, either alone or superimposed on chronic hypertension, is the most dangerous. In the United States from 2011 to 2015, 7 percent of pregnancy-related maternal deaths were caused by preeclampsia or eclampsia (Petersen, 2019). Most hypertension-related deaths are deemed preventable (Katsuragi, 2019). In response, Joint Commission (2019) accredited hospitals are now required to track their recognition and timely treatment of hypertension.
In 2018, a workshop to study preeclampsia was convened by the National Heart, Lung, and Blood Institute. This builds on the prior work of the American College of Obstetricians and Gynecologists’ Task Force on Hypertension in Pregnancy (2013). Its purpose was to review topics regarding all aspects of preeclampsia and to recommend future research areas. Many of these topics are discussed throughout this chapter and Chapter 41.
TERMINOLOGY AND DIAGNOSIS
To codify the classification of hypertensive disorders of pregnancy, the American College of Obstetricians and Gynecologists (2013, 2020) describes four types of hypertensive disease:
Preeclampsia and eclampsia syndrome
Chronic hypertension of any etiology
Preeclampsia superimposed on chronic hypertension
Gestational hypertension, in which definitive evidence for the preeclampsia syndrome does not develop and hypertension resolves by 12 weeks postpartum.
This classification aims to differentiate preeclampsia syndrome, which is potentially more ominous, from other hypertensive disorders.
Diagnosis of Hypertensive Disorders
Hypertension is diagnosed empirically when systolic and diastolic blood pressures exceed 140 mm Hg and 90 mm Hg, respectively. Korotkoff phase V is used to define diastolic pressure.
Previously for pregnant women, increases of 30 mm Hg systolic or 15 mm Hg diastolic above blood pressure values taken at midpregnancy had also been used as diagnostic criteria, even when absolute values were <140/90 mm Hg. These incremental changes are no longer used to define hypertension. However, blood pressure surveillance in these gravidas is reasonable because eclamptic seizures develop in some whose blood pressures have stayed below 140/90 mm Hg (Alexander, 2006).
In other cases, mean arterial pressures that suddenly rise but that still lie in normal range—“delta hypertension”—may signify preeclampsia (Macdonald-Wallis, 2012; Zeeman, 2007).
We use this term to describe a relatively acute rise in blood pressure in individual patients, albeit some still with pressures <140/90 mm Hg (Fig. 40-1). Some of these women will go on to have obvious preeclampsia, and some even develop eclamptic seizures or hemolysis, elevated liver enzyme levels, and low platelet count (HELLP) syndrome.
Schematic of normal reference ranges for mean arterial ...