Table 1.

Classification of Hypertensive Disorders of Pregnancy

Chronic hypertension	BP ≥140/±90 mm Hg before pregnancy or before the 20th week of gestation
Preeclampsia‐eclampsia	A pregnancy‐specific disorder that is a multisystem disease characterized by hypertension ≥140/±90 mm Hg on ≥2 occasions at least 6 hours apart, and proteinuria ≥300 mg in a 24‐hour urine collection, after 20 weeks' gestation. The convulsive form of preeclampsia is eclampsia and affects 0.1% of all pregnancies.
Preeclampsia superimposed on chronic hypertension	Up to 30% of women with chronic hypertension develop preeclampsia, as heralded by the occurrence of de novo proteinuria in the third trimester. In women with chronic hypertension and preexisting proteinuria (ie, before 20 weeks of gestation), the diagnosis of superimposed preeclampsia is likely with any of the following findings: sudden increase in proteinuria, sudden worsening of previously well‐controlled BP, new‐onset thrombocytopenia, or elevated liver function tests.
Gestational hypertension	New onset of hypertension ≥140/±90 mm Hg on ≥2 occasions at least 6 hours apart, after 20 weeks' gestation, in the absence of proteinuria, <300 mg in a 24‐hour urine collection. If BP returns to normal by 12 weeks postpartum, the diagnosis of transient hypertension of pregnancy can be assigned. If elevated BP persists, the diagnosis of chronic hypertension is made.

Abbreviations: BP, blood pressure.