Hypertension during pregnancy: Epidemiology, definition

Hypertension in pregnancy has several forms that differ by their mechanisms and their consequences for mothers and fetus. Chronic hypertension is defined by SBP >= 140 mm Hg or DBP >= 90 mm Hg before pregnancy or before the 20th week of amenorrhea. Gestational hypertension is defined by SBP >= 140 mm Hg or DBP >= 90 mm Hg during or after the 20th week of amenorrhea. Preeclampsia is the occurrence of hypertension and proteinuria after 20 weeks of amenorrhea. Severe preeclampsia is accompanied by clinical signs and symptoms indicating visceral pain. The HELLP syndrome is a severe preeclampsia accompanied by intravascular hemolysis and hepatic cytolysis. Eclampsia is characterized by seizures of the tonic-clonic type. A chronic hypertension is observed in 1-5% of pregnancies. Gestational hypertension without proteinuria appears in 5-6% of pregnancies. A preeclampsia develops in 1-2% of pregnancies, but much more frequently (up 34%) in the presence of risk factors. High blood pressure during pregnancy remains, by its complications, the leading cause of maternal morbidity and mortality.