Pregnancy-Induced Hypertension

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Pregnancy-induced hypertension is the leading cause of maternal death in the United States. It is a multi-system failure that occurs only during pregnancy and regresses after delivery. It is thought to be caused by an imbalance in thromboxane A2 (a vasoconstrictor) and placental prostacyclin (a platelet inhibitor).

Early signs of PIH include high blood pressure, sudden weight gain, edema, and proteinuria. Late signs of PIH manifest as visual acuity changes, headaches, and abdominal pain due to the impact on multiple organ systems.

Treatment is aimed at prevention of complications and convulsions due to eclampsia.

Pregnancy-induced hypertension (PIH), once known as “toxemia of pregnancy” (this term is no longer acceptable or used), is the most common medical complication of pregnancy reported and is the leading cause of maternal death in the United States, accounting for approximately 15-18% of deaths. It occurs in approximately 6-8% of pregnancies. PIH is a multiorgan disease process and develops as a consequence of pregnancy. It progresses rapidly and regresses in the postpartum period. Delivery is the only definitive treatment for this condition.

PREDISPOSING FACTORS AND CAUSES

Although there are no known causes for PIH, several factors contribute to its development. This disease usually occurs if a woman is a primipara, carrying multiple gestations, of advanced maternal age, diabetic, or obese. The incidence rate is higher among African-American women, those with an Rh incompatibility, and those with a prior history of lupus or renal disease.

PIH is thought to be caused by an imbalance of the placental prostacyclin, a vasodilator that inhibits platelet aggregation, and thromboxane A₂, a vasoconstrictor that stimulates platelet aggregation, resulting in vasospasm, which in turn increases peripheral vascular resistance.