Pregnancy is a cardiovascular and metabolic challenge to the human female body. This review summarizes current knowledge on the regulation of blood pressure and plasma volume in normal and hypertensive pregnant women. During pregnancy, systemic vascular resistance and blood pressure decrease, whereas cardiac output and blood volume increase to safeguard an adequate circulation in the utero-placental arterial bed. Hypertension affects 10% of all pregnancies and is accompanied by an increase in foetal and maternal morbidity and mortality. Hypertension in pregnancy includes a wide spectrum of conditions, including pre-eclampsia and eclampsia, pre-eclampsia superimposed on chronic hypertension, chronic hypertension, and gestational hypertension. Endothelial dysfunction, oxidative stress and an exaggerated inflammatory response are features related to hypertensive disorders. Microangiopathic disorders can easily mimic hypertensive disorders during pregnancy. Although they have some symptoms in common, they require another type of management. To reduce the risk of maternal and foetal complications due to haemodynamic maladaptations, the current management includes rest at home or in the hospital, close monitoring of maternal and foetal signs and symptoms, early start of antihypertensive therapy, and timely delivery regarding maternal and foetal survival chances. Thresholds to initiate blood pressure lowering treatment during pregnancy are 160 mmHg systole or 110 mmHg diastole. Below these thresholds, treatment must be individualized because current evidence does not support aggressive medical interventions. Alpha-methyldopa and dihydropyridinic calcium channel blockers are among the recommended antihypertensives.