Hypertension is a common medical complication of pregnancy. Although 75-80 % of women with preexisting essential hypertension will have uncomplicated pregnancies, the presence of secondary forms of hypertension adds considerably to both maternal and fetal morbidity and mortality. Renovascular hypertension, pheochromocytoma, and Cushing's syndrome in particular are associated with accelerating hypertension, superimposed preeclampsia, preterm delivery, and fetal loss. Primary aldosteronism is a more heterogeneous disorder; there are well-documented cases where blood pressure and hypokalemia are improved during pregnancy due to elevated levels of progesterone. However, superimposed preeclampsia, worsening hypertension, and early delivery are also reported. When possible, secondary forms of hypertension should be diagnosed and treated prior to conception in order to avoid these complications.
