Pregnancy may be complicated by hypertension either as a pre-existing condition or as a newly diagnosed condition during pregnancy. Each condition carries with it significant risks and important management considerations that may impact the well-being of both the mother and fetus. Pre-eclampsia, a multisystem disorder that is marked by pregnancy-induced hypertension and proteinuria, is a significant obstetrical risk that affects approximately 5 % of pregnancies.

The exact cause of pre-eclampsia is unknown, but its multisystem complications are well described. Physiologically, pre-eclampsia is marked by increased vascular resistance, platelet aggregation, and endothelial dysfunction. Clinically, pre-eclampsia may be identified with hypertension (occurring after 20 weeks’ gestation), proteinuria, HELLP syndrome (Hemolysis, Elevated Liver enzymes, Low Platelets), and seizures (eclampsia).

Chronic hypertension is defined as hypertension (repeated BP readings of systolic ≥140 or diastolic ≥90 mmHg) existing prior to pregnancy or first diagnosed prior to 20 weeks’ gestation. Obstetrical complications associated with chronic hypertension include increased risk for pre-eclampsia (discussed later), abruptio placentae, premature delivery, IUGR, fetal demise, and fetal stress. Pregnancy itself may worsen hypertensive renal disease. The majority of such complications occur in women with diastolic BPs higher than 110 mmHg although such complications may occur in women with lower BP.

Pre-eclampsia occurs in approximately 5 % of all pregnancies and may be associated with many of the same obstetrical risks as chronic hypertension (Table 14.1): HELLP syndrome (10–20 %), abruptio placentae (1–4 %), and eclampsia (<1 %). Rarely, it may also be associated with maternal stroke or death. Complications for the neonate include IUGR (10–25 %), preterm delivery (15–67 %), and perinatal death (1–2 %). For both the mother and infant, the presence of pre-eclampsia may be associated with long-term cardiovascular morbidity.