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Hypertension in Pregnancy

By

Lara A. Friel

, MD, PhD, University of Texas Health Medical School at Houston, McGovern Medical School

Last full review/revision Jun 2021| Content last modified Jun 2021
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Recommendations regarding classification, diagnosis, and management of hypertensive disorders (including preeclampsia) are available from the American College of Obstetricians and Gynecologists (ACOG [1 General reference Recommendations regarding classification, diagnosis, and management of hypertensive disorders (including preeclampsia) are available from the American College of Obstetricians and Gynecologists... read more ]).

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:

  • 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 abruptio placentae. 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

Diagnosis of Hypertension in Pregnancy

  • Tests to rule out other causes of hypertension

BP 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 Gestational Trophoblastic Disease Gestational trophoblastic disease is proliferation of trophoblastic tissue in pregnant or recently pregnant women. Manifestations may include excessive uterine enlargement, vomiting, vaginal... read more Gestational Trophoblastic Disease , tests to rule out other causes of hypertension (eg, renal artery stenosis Renal Artery Stenosis and Occlusion Renal artery stenosis is a decrease in blood flow through one or both of the main renal arteries or their branches. Renal artery occlusion is a complete blockage of blood flow through one or... read more Renal Artery Stenosis and Occlusion , coarctation of the aorta Coarctation of the Aorta Coarctation of the aorta is a localized narrowing of the aortic lumen that results in upper-extremity hypertension, left ventricular hypertrophy, and malperfusion of the abdominal organs and... read more , Cushing syndrome Cushing Syndrome Cushing syndrome is a constellation of clinical abnormalities caused by chronic high blood levels of cortisol or related corticosteroids. Cushing disease is Cushing syndrome that results from... read more Cushing Syndrome , SLE Systemic Lupus Erythematosus (SLE) Systemic lupus erythematosus is a chronic, multisystem, inflammatory disorder of autoimmune etiology, occurring predominantly in young women. Common manifestations may include arthralgias and... read more Systemic Lupus Erythematosus (SLE) , pheochromocytoma Pheochromocytoma A pheochromocytoma is a catecholamine-secreting tumor of chromaffin cells typically located in the adrenals. It causes persistent or paroxysmal hypertension. Diagnosis is by measuring catecholamine... read more ) should be considered.

Treatment of Hypertension in Pregnancy

  • For mild hypertension, conservative measures followed by antihypertensives if needed

  • Methyldopa, beta-blockers, or calcium channel blockers tried first

  • Avoidance of angiotensin-converting enzyme (ACE) inhibitors, angiotensin II receptor blockers (ARBs), and aldosterone antagonists

  • 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 drugs 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. Women who were taking methyldopa, a beta-blocker, a calcium channel blocker, or a combination before pregnancy may continue to take these drugs. However, ACE inhibitors and ARBs should be stopped once pregnancy is confirmed.

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 drugs 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 Fetal Monitoring Labor consists of a series of rhythmic, involuntary or medically induced contractions of the uterus that result in effacement (thinning and shortening) and dilation of the uterine cervix. The... read more 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.

Drugs

First-line drugs for hypertension during pregnancy include

  • Methyldopa

  • Beta-blockers

  • Calcium channel blockers

Initial methyldopa dose is 250 mg orally twice a day, increased as needed to a total of 2 g a day unless excessive somnolence, depression, or symptomatic orthostatic hypotension occurs.

The most commonly used beta-blocker is labetalol (a beta-blocker with some alpha-1 blocking effects), which can be used alone or with methyldopa when the maximum daily dose of methyldopa has been reached. Usual dose of labetalol is 100 mg twice or 3 times a day, increased as needed to a total maximum daily dose of 2400 mg. Adverse effects of beta-blockers include increased risk of fetal growth restriction, decreased maternal energy levels, and maternal depression.

Extended-release nifedipine, a calcium channel blocker, may be preferred because it is given once a day (initial dose of 30 mg; maximum daily dose of 120 mg); adverse effects include headaches and pretibial edema. Thiazide diuretics are only used to treat chronic hypertension during pregnancy if the potential benefit outweighs the potential risk to the fetus. Dose may be adjusted to minimize adverse effects such as hypokalemia.

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 (spironolactone and eplerenone) should be avoided because they may cause feminization of a male fetus.

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.

  • If drug therapy is necessary, start with methyldopa, a beta-blocker, or a calcium channel blocker.

  • Do not use ACE inhibitors, ARBs, or aldosterone antagonists.

  • Consider hospitalization or termination of pregnancy if BP is > 180/110 mm Hg.

Drugs Mentioned In This Article

Drug Name Select Trade
ALDACTONE
ADALAT CC, PROCARDIA
No brand name
INSPRA
No US brand name
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