Recommendations regarding classification, diagnosis, and management of hypertensive disorders (including preeclampsia) are available from the American College of Obstetricians and Gynecologists (ACOG [1]).
(See also Hypertension.)
In 2017, the American College of Cardiology (ACC) and the American Heart Association (AHA) released new guidelines for the evaluation of high blood pressure (BP). They lowered the definitions for hypertension as follows:
Normal: < 120/80 mm Hg
Elevated: 120 to 129/< 80 mm Hg)
Stage 1 hypertension: 130 to 139/80 to 89 mm Hg
Stage 2 hypertension: ≥ 140/90 mm Hg
ACOG defines chronic hypertension as systolic BP ≥ 140 mm Hg or diastolic BP ≥ 90 mm Hg on 2 occasions before 20 weeks gestation. Data on the effect of hypertension as defined by the ACC/AHA during pregnancy are limited. Thus, pregnancy management is likely to evolve.
Hypertension during pregnancy can be classified as one of the following:
Chronic: BP is high before pregnancy or before 20 weeks gestation. Chronic hypertension complicates about 1 to 5% of all pregnancies.
Gestational: Hypertension develops after 20 weeks gestation (typically after 37 weeks) and remits by 6 weeks postpartum; it occurs in about 5 to 10% of pregnancies, more commonly in multifetal pregnancy.
Both types of hypertension increase risk of preeclampsia and eclampsia and of other causes of maternal mortality or morbidity, including
Hypertensive encephalopathy
Stroke
Renal failure
Left ventricular failure
HELLP syndrome (hemolysis, elevated liver enzymes, and low platelet count)
Risk of fetal mortality or morbidity increases because of decreased uteroplacental blood flow, which can cause vasospasm, growth restriction, hypoxia, and placental abruption. Outcomes are worse if hypertension is severe (systolic BP ≥ 160 mm Hg, diastolic BP ≥ 110 mm Hg, or both) or accompanied by renal insufficiency (eg, creatinine clearance < 60 mL/min, serum creatinine > 2 mg/dL [> 180 μmol/L]).
General reference
1. American College of Obstetricians and Gynecologists, Task Force on Hypertension in Pregnancy: Hypertension in pregnancy. Report of the American College of Obstetricians and Gynecologists’ Task Force on Hypertension in Pregnancy. Obstet Gynecol 122 (5):1122–1131, 2013. doi: 10.1097/01.AOG.0000437382.03963.88
Diagnosis of Hypertension in Pregnancy
Tests to rule out other causes of hypertension
Blood pressure is measured routinely at prenatal visits. If severe hypertension occurs for the first time in pregnant women who do not have a multifetal pregnancy or gestational trophoblastic disease, tests to rule out other causes of hypertension (eg, renal artery stenosis, coarctation of the aorta, Cushing syndrome, systemic lupus erythematosus, pheochromocytoma) should be considered.
Treatment of Hypertension in Pregnancy
For mild hypertension, conservative measures followed by antihypertensives if needed
For moderate or severe hypertension, antihypertensive therapy, close monitoring, and, if condition worsens, possibly termination of pregnancy or delivery, depending on gestational age
Recommendations for chronic and gestational hypertension are similar and depend on severity. However, chronic hypertension may be more severe. In gestational hypertension, the increases in BP often occur only late in gestation and may not require treatment.
Treatment of mild to moderate hypertension without renal insufficiency during pregnancy is controversial; the issues are whether treatment improves outcome and whether the risks of drug treatment outweigh risks of untreated disease. Because the uteroplacental circulation is maximally dilated and cannot autoregulate, decreasing maternal BP with medications may abruptly decrease uteroplacental blood flow. Diuretics reduce effective maternal circulating blood volume; consistent reduction increases risk of fetal growth restriction. However, hypertension with renal insufficiency is treated even if hypertension is mild or moderate.
For mild to moderate hypertension (systolic BP 140 to 159 mm Hg or diastolic BP 90 to 109 mm Hg) with labile BP, reduced physical activity may decrease BP and improve fetal growth, making perinatal risks similar to those for women without hypertension. However, if this conservative measure does not decrease BP, many experts recommend drug therapy. In pregnant women with mild chronic hypertension, a strategy of targeting a BP < 140/90 mm Hg was associated with decreased incidence of preeclampsia and preterm birth, without increase risk of small-for-gestational-age birth weight (1
For severe hypertension (systolic BP ≥ 160 mm Hg or diastolic BP ≥ 110 mm Hg), drug therapy is indicated. Risk of complications—maternal (progression of end-organ dysfunction, preeclampsia) and fetal (prematurity, growth restriction, stillbirth)—is increased significantly. Several antihypertensives may be required.
For systolic BP > 180 mm Hg or diastolic BP > 110 mm Hg, immediate evaluation is required. Multiple medications are often required. Also, hospitalization may be necessary for much of the latter part of pregnancy. If the woman’s condition worsens, pregnancy termination may be recommended.
All women with chronic hypertension during pregnancy should be taught to self-monitor BP, and they should be evaluated for target organ damage. Evaluation, done at baseline and periodically thereafter, includes
Serum creatinine, electrolytes, and uric acid levels
Liver function tests
Platelet count
Urine protein assessment
Usually funduscopy
Maternal echocardiography should be considered if women have had hypertension for > 4 years. After initial ultrasonography to evaluate fetal anatomy, ultrasonography is done monthly starting at about 28 weeks to monitor fetal growth; antenatal testing often begins at 32 weeks. Ultrasonography to monitor fetal growth and antenatal testing may start sooner if women have additional complications (eg, renal disorders) or if complications (eg, growth restriction) occur in the fetus. Delivery should occur by 37 to 39 weeks but may be induced earlier if preeclampsia or fetal growth restriction is detected or if fetal test results are nonreassuring.
Pharmacologic treatment
First-line medications for hypertension during pregnancy include
Beta-blockers
Calcium channel blockers
Several classes of antihypertensives are usually avoided during pregnancy:
ACE inhibitors are contraindicated because risk of fetal urinary tract abnormalities is increased.
ARBs are contraindicated because they increase risk of fetal renal dysfunction, lung hypoplasia, skeletal malformations, and death.
Aldosterone antagonists
Treatment reference
1. Tita AT, Szychowski JM, Boggess K, et al: Treatment for Mild Chronic Hypertension during Pregnancy. N Engl J Med 386(19):1781-1792, 2022. doi:10.1056/NEJMoa2201295
Key Points
Both chronic and gestational hypertension increase risk of preeclampsia, eclampsia, other causes of maternal mortality or morbidity (eg, hypertensive encephalopathy, stroke, renal failure, left ventricular failure, HELLP syndrome), and uteroplacental insufficiency.
Check for other causes of hypertension if severe hypertension occurs for the first time in a pregnant woman who does not have a multifetal pregnancy or gestational trophoblastic disease.
Do not use ACE inhibitors, ARBs, or aldosterone antagonists.
Consider hospitalization or termination of pregnancy if BP is > 180/110 mm Hg.
