High Blood Pressure in Pregnant Women

Preeclampsia is a serious condition that is a leading cause of maternal death worldwide and occurs in around 7.5% of all pregnancies. Preeclampsia is defined as the new onset of hypertension and either proteinuria or end-organ dysfunction after 20 weeks of gestation in a previously normotensive woman. The blood pressure of more than 140/90 mmHg and more than 300 mg protein in 24-hour urine meet the criteria. The pathophysiology of preeclampsia involves abnormal formation or placement of the placenta and defective growth of placental blood vessels. Dysfunctional development of the early embryo and a generally heightened, systemic inflammatory response in the mother are likely involved as well.

Preeclampsia is a multisystem disorder with a spectrum that ranges from mild to severe. The severity determines the management and the decision about when to deliver the baby. Preeclampsia is considered severe if blood pressure is ≥ 160/110 mmHg on two occasions at least 4 hours apart and there is evidence of end-organ dysfunction such as cerebral or visual disturbances such as headache and photopsia, hepatic abnormality such as epigastric pain with elevations in liver enzymes more than twice normal, thrombocytopenia (< 100,000 platelets/µL), renal dysfunction with serum creatinine ≥ 1.1 mg/dL, or pulmonary edema.3

Certain risk factors that predispose pregnant women to preeclampsia include: nulliparity, extremes of reproductive age (< 15 and > 35 years of age), African-American race, history of preeclampsia in a first-degree female relative, history of preeclampsia in a prior pregnancy, diabetes, chronic vascular or renal disease, chronic hypertension, and multiple gestations.3

Although most affected pregnancies with mild preeclampsia deliver near or at term with good maternal and fetal outcomes, these pregnancies are at increased risk for serious maternal and/or fetal mortality. Fetal risks include growth restriction, oligohydramnios, placental infarction, placental abruption, uteroplacental insufficiency, perinatal death. Maternal risks include: central nervous system manifestations such as seizures and stroke, disseminated intravascular coagulation and its complications, increased likelihood of cesarean delivery, renal failure, hepatic failure, and death.5

Many guidelines and recommendations are available to the clinician treating preeclampsia. Management includes control of blood pressure with antihypertensives, the use of low-dose aspirin for prevention, and magnesium sulfate when indicated. Treatment of severe hypertension (≥ 160/110 mmHg) is necessary to prevent maternal cerebrovascular, cardiac, and renal complications.1 However, delivery is the only definitive treatment to prevent progression of maternal or fetal complications.1 In general, signs and symptoms of preeclampsia resolve with delivery. Timing of delivery is based upon gestational age, the severity of preeclampsia, and maternal and fetal condition. All term pregnancies (≥ 37 weeks) with mild or severe preeclampsia are delivered promptly. For preterm pregnancies (≤ 37 weeks), those with severe symptoms are delivered and those with mild symptoms are managed conservatively with bed rest and close fetal and maternal surveillance.4

General management recommendations include the “continued treatment of women with a remote history of preeclampsia.” The treatment of preeclampsia should not end after pregnancy, or even after the childbearing years. These women need to be followed in later life for the development of cardiovascular disease and advised regarding any modifiable risk factors.1

Lylla Ngo, M.D

Thomas Hale, Ph.D.

References:

1. Berzan E, Doyle R, Brown CM: Treatment of preeclampsia: current approach and future perspectives. Current Hypertension Reports. 2014 Sep 2014;16(9):473.

2. Melchiorre K, Sharma R, Thilaganathan B.Cardiovascular implications in preeclampsia: an overview. Circulation. Aug 19 2014;130(8):703-14.

3. August P, Sibai B. Preeclampsa: Clinical features and diagnosis. UpTodate. 8/13/2014 ed; 2014.

4. Norwits ER, Repke JT. Preeclampsia: Management and prognosis. UpTodate. 8/4/2014 ed; 2014.

5. Decherney AH, Nathan L,  Laufer N, Roman AS. Current diagnosis and treatment: Obstetrics and Gynecology. Lange 11th edition; 2013.