Gestational hypertension and preeclampsia: are they the same disease?

Abstract

P complicating 5% to 8% of pregnancies, has been traditionally defined by an elevated blood pressure (over 140/90 mmHg on at least 2 occasions at least 6 hours apart) and proteinuria, at or beyond 20 weeks’ gestation.1,2 In 2013, the American College of Obstetricians and Gynecologists’ Task Force on Hypertension in Pregnancy recommended that the definition of PE should be extended to include cases without evidence of proteinuria, provided that the hypertension is accompanied by evidence of end-organ involvement.2 PE is associated with an increased risk of adverse pregnancy outcome, including prematurity, placental abruption, and intrauterine growth restriction.3 In contrast, gestational hypertension is defined by an elevated BP at or beyond 20 weeks’ gestation in the absence of proteinuria1,2 and is considered to be a transient condition (Figure 1).1 The development of proteinuria later in pregnancy changes the final diagnosis to preeclampsia. Otherwise, the final diagnosis is determined according to a re-evaluation of BP recordings at approximately three months postpartum. For women who are then normotensive (the most common scenario4), the final diagnosis is transient HTN of pregnancy (Figure 1). Persistence of GHTN for more than three months postpartum is consistent with a diagnosis of chronic hypertension. For clinicians who provide management for women with hypertension in pregnancy, several issues are of interest with respect to the importance of distinguishing between GHTN and PE. The first is the long-standing controversy of whether GHTN is an independent clinical entity or merely a mild or pre-onset form of PE. A second and more practical issue is determining the risk of progression of GHTN to PE. A third issue is quantifying the degree to which GHTN is associated with adverse pregnancy outcomes. Although GHTN is the most common form of hypertension in pregnancy,5 most researchers have focused their efforts on PE because of its implications for maternal–fetal health, whereas information about the implications of a diagnosis of GHTN is much more limited. Herein, we attempt to summarize the most up to date information available to address these important clinical questions.