Preeclampsia and High Blood Pressure During Pregnancy

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What is high blood pressure? What is preeclampsia? How are they related?

When you have high blood pressure (hypertension), the force of blood against your artery walls is stronger than normal. If you have high blood pressure during a pregnancy, you must have more frequent checkups.

High blood pressure can remain mild during pregnancy, or it can become dangerously high and need treatment. It can also turn out to be a sign of preeclampsia, a pregnancy-related problem that can become life-threatening for you and/or your fetus.

High blood pressure

Normally, a pregnant woman's blood pressure drops during the second trimester and then returns to normal levels by the end of the third trimester. However, in 10% of pregnant women, blood pressure begins to increase to abnormally high levels in the second or third trimester.¹ This is sometimes called pregnancy-induced hypertension.

• Mild high blood pressure during pregnancy is not necessarily dangerous by itself. However, it is closely monitored because it can be a sign of a more serious condition, such as preeclampsia. After delivery, mild high blood pressure that has not become worse during the pregnancy and has returned to normal within 12 weeks can be termed "transient hypertension of pregnancy."
• Severe high blood pressure limits the blood oxygen supply to your fetus, increasing the risk for poor fetal growth, early separation of the placenta from the uterine wall (placenta abruptio), and stillbirth. For this reason, you are likely to be treated with medicine to lower your blood pressure if your diastolic blood pressure reading is about 105 or higher (this is the second, or lower, number).

Long-term (chronic) high blood pressure is a lifelong yet treatable condition. The greatest risk for pregnant women with chronic high blood pressure is their 1-in-4 chance of developing preeclampsia.² When the two conditions occur together, your risk of complications from high blood pressure increases, as does your risk of complications from preeclampsia.

Preeclampsia

Preeclampsia is defined as the new onset of high blood pressure after 20 weeks of pregnancy, usually with higher-than-normal levels of protein found in a urine sample. Blood pressure is considered to be high if the first number (systolic) is more than 140 millimeters of mercury (mm Hg), or the second number (diastolic) is more than 90 mm Hg, or both. For example, blood pressure of 140/95 (say "140 over 95") or 150/85 is high.

In its most severe form, preeclampsia is a life-threatening pregnancy problem. Although it is not well understood, preeclampsia seems to start with a placenta that doesn't grow the usual network of blood vessels deep into the uterine wall. This leads to poor blood circulation through the placenta.³ In addition to causing mild to severe high blood pressure, preeclampsia can also cause problems with blood supply to the fetus and sometimes with the woman's liver, kidney, and brain functions. Women with severe preeclampsia can develop life-threatening seizures (eclampsia).

Preeclampsia only occurs during or just after pregnancy. It affects about 5% of all pregnancies, most commonly first-time pregnancies.⁴ Although preeclampsia may last for up to 6 weeks after delivery, it always goes away after a pregnancy.

Preeclampsia probably does not cause future high blood pressure. Instead, experts think that women who have preeclampsia also have a higher-than-normal risk of chronic high blood pressure after pregnancy or later in life.⁵

Both high blood pressure and preeclampsia can develop gradually or occur suddenly and can range from mild to severe. If you develop high blood pressure during pregnancy, there is no way of knowing whether it is a first sign of preeclampsia. This is why you are closely monitored for signs of preeclampsia throughout your pregnancy.

What causes high blood pressure during pregnancy? What causes preeclampsia?

Both preeclampsia and high blood pressure during pregnancy are caused by complex events in the body. Researchers are still studying these conditions.

Preeclampsia appears to have a genetic component. If your mother had preeclampsia while she was pregnant with you, you have an increased risk of developing preeclampsia during pregnancy. Similarly, if your partner in the pregnancy was born from a pregnancy affected by preeclampsia, your risk of developing preeclampsia is also higher than normal.⁶

Experts also suspect that some women develop preeclampsia as a type of immune system reaction to the father's sperm, the placenta, or the fetus.⁵

Preeclampsia has been linked to placenta problems (such as a twin pregnancy with a larger placenta and poorer blood circulation than normal), high blood pressure, conditions that can lead to high blood pressure (such as obesity and polycystic ovary syndrome), and diabetes.⁵

What are the symptoms?

High blood pressure usually doesn't cause noticeable symptoms. However, severely high blood pressure sometimes causes headaches and shortness of breath or changes in vision.

Mild preeclampsia also doesn't typically cause noticeable symptoms. Preeclampsia can, however, cause rapid weight gain, problems with blood clotting, and sudden, persistent swelling of the hands and face. Severe preeclampsia causes signs of brain or organ trouble, including a severe headache, vision problems, breathing problems, abdominal pain, and decreased urination.

How are high blood pressure and preeclampsia diagnosed?

Because low-to-moderate high blood pressure and preeclampsia typically develop without causing symptoms, it is important to have a blood pressure check and a urine screen for higher-than-normal protein levels (a sign of preeclampsia) at each prenatal visit.

Your blood pressure is measured with a blood pressure cuff during every prenatal checkup. A sudden increase in blood pressure is typically the first sign of a possible problem.

Preeclampsia is diagnosed when blood pressure rises to 140/90 mm Hg after 20 weeks of pregnancy. Either the first number (systolic) could be higher than 140, or the second number could be higher than 90, or both. Many women also have increased levels of protein in their urine. However, if your blood pressure has recently gone up and you now have a headache or abdominal pain, tell your health professional right away. Preeclampsia can sometimes cause these signs and symptoms before protein shows up in a urine screen.³

How is high blood pressure treated during pregnancy? How is preeclampsia treated?

Mild-to-moderate long-term (chronic) high blood pressure during pregnancy is closely monitored. Blood pressure levels of 140/90 mm Hg to 179/109 mm Hg can sometimes be treated with little or no medicine.² Severe high blood pressure during pregnancy is typically treated with medicine to prevent harm to the mother and fetus.

Depending on severity, preeclampsia may be treated with a medicine to prevent seizures (eclampsia), or with a blood pressure medicine, or with both.

Frequently Asked Questions

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	Monitoring your blood pressure at home

The causes of preeclampsia and high blood pressure during pregnancy are poorly understood. In fact, preeclampsia is sometimes called the "disease of theories," and its cause is the subject of active research.⁷

Most experts believe that preeclampsia starts with a poorly developed placenta that doesn't circulate blood normally.³ However, the cause of the placenta disorder isn't yet clear. Nor is it known why the mother's body then develops high blood pressure. So far, a number of possible factors are thought to play a part in preeclampsia, including:

• Family history (genetics). The tendency to develop preeclampsia appears to run in families. Inherited factors (genes) seem to make a woman more likely to develop preeclampsia. Similarly, men with a family history of preeclampsia are more likely to father a preeclampsia-affected pregnancy than men with no such family history.⁶
• An abnormal immune system response. Preeclampsia occurs most often in women who are pregnant for the first time and in women who have been pregnant before but now have a first pregnancy with a different man.^{3, 4} Experts think that some women may have an immune system reaction that triggers the condition.⁵ Exposure to an antigen from the father (in the growing placenta or fetus, for example) may trigger an immune response in the woman's body. This immune response may result in narrowing of the blood vessels throughout the body, causing higher blood pressure and other problems.
• A biochemical factor that causes the blood vessels to narrow, raising blood pressure. Preeclampsia may be the body's reaction to the poorly functioning placenta. Or, both the poorly developed placenta and preeclampsia symptoms may be caused by the same factor. This process is not yet well understood.⁸
• Underlying diabetes or other diseases affecting blood vessels. Conditions that cause blood vessel problems (such as lupus, preexisting high blood pressure, or diabetes) increase the risk of preeclampsia.³

High blood pressure

If you have developed high blood pressure, you will probably not have any symptoms. It usually requires a blood pressure check with a blood pressure cuff and stethoscope to detect elevated blood pressure.

Blood pressure measured at 140/90 millimeters of mercury (mm Hg) or higher is classified as high (hypertensive) and 160/110 mm Hg or higher is classified as severe.

Preeclampsia

In mild preeclampsia, systolic blood pressure is over 140 mm Hg, or diastolic blood pressure is over 90 mm Hg, or both, for two measurements taken at least 6 hours apart. In addition, protein in the urine is usually higher than normal. High urine protein is 300 milligrams (mg) measured in 24 hours or protein consistently showing 1+ on a dipstick.

Symptoms of preeclampsia can develop gradually or suddenly. Symptoms include:

• Swelling of the hands and face that does not go away during the day. (If you have no other signs or symptoms of preeclampsia, this swelling is probably a sign of normal pregnancy.)
• Rapid weight gain [more than 2 lb (0.91 kg) per week or 6 lb (2.72 kg) per month].
• Bleeding from a cut or injury that lasts longer than usual.

Severe preeclampsia

In severe preeclampsia, systolic blood pressure is over 160 mm Hg, or diastolic blood pressure is over 110 mm Hg, or both.⁵

As blood circulation to the organs decreases, more severe symptoms can develop, including:

• A severe headache that will not go away with medicine such as acetaminophen.
• Blurred or dimming vision, spots in the visual field, or periods of blindness.
• Decreased urination [less than 2 cups (473 mL) in 24 hours].
• Persistent abdominal pain or tenderness, especially on the upper right side.
• Difficulty breathing, especially when lying flat.
• HELLP syndrome.

HELLP syndrome is a life-threatening liver disorder. It is usually caused by preeclampsia, although women can get HELLP without having either preeclampsia or eclampsia first⁹. Get emergency medical treatment if you have several symptoms of HELLP syndrome. Symptoms include:

• Pain in the upper right abdomen (liver).
• Shoulder, neck, and other upper body pain (this pain also originates in the liver).
• Fatigue.
• Nausea and vomiting.
• Headache.
• Vision problems.

HELLP is short for Hemolysis (destruction of red blood cells), Elevated Liver enzymes (which indicate liver damage), and Low Platelet count.

Severe preeclampsia increases the risk of seizures (eclampsia).

Eclampsia

When preeclampsia leads to seizures that are not from any other cause, it is called eclampsia. Eclampsia is a life-threatening condition for both a mother and her fetus. During a seizure, the oxygen supply to the fetus is drastically reduced. Call 911 any time a pregnant woman has a seizure.

Normally, a pregnant woman's blood pressure drops during the second trimester and then gradually returns to normal throughout the remainder of her pregnancy. However, in 10% of pregnant women, blood pressure begins to increase to abnormally high levels (hypertension) sometime after 20 weeks of pregnancy.¹ This is occasionally referred to as pregnancy-induced hypertension. Less commonly, this change in blood pressure develops during the first days after childbirth.

At the first sign of high blood pressure during pregnancy, your health professional cannot predict whether it will remain mild, become severe, or turn out to be an early sign of preeclampsia. If you are developing preeclampsia, your urine test (urine screen) will probably show increased protein levels before long. This sign that your kidneys are being affected by the condition doesn't develop right away.

If you aren't certain that you had normal blood pressure before pregnancy, it is possible that you have preexisting chronic high blood pressure. If so, your blood pressure may remain high after your pregnancy.

High blood pressure that develops during pregnancy

High blood pressure that develops before the 20th week of pregnancy is usually a sign of ongoing (chronic) high blood pressure or short-term (transient) high blood pressure. On rare occasions, it is an early sign of preeclampsia.

High blood pressure that occurs after midpregnancy is more likely to be a sign that you are developing preeclampsia. This can be anytime after the 20th week.²

Chronic high blood pressure and pregnancy

Women with chronic high blood pressure (hypertension) who become pregnant normally have a drop in blood pressure during the first two trimesters. During the late second or in the third trimester, however, blood pressure returns to higher-than-normal levels. Following delivery, their blood pressure remains high. For more information, see the topic High Blood Pressure (Hypertension).

Chronic high blood pressure increases your risk of preeclampsia during pregnancy. Of women with chronic high blood pressure who become pregnant, about 1 in 4 (25%) develop preeclampsia during pregnancy.² (Of all pregnancies, only about 5% of women develop preeclampsia.⁴)

Most women with chronic high blood pressure who are otherwise healthy have a low risk for other cardiovascular problems during pregnancy.

Preeclampsia

Preeclampsia affects your blood pressure, placenta, liver, blood, kidneys, and brain. Preeclampsia can be mild or severe, and it may get worse gradually or rapidly. Both you and your fetus can potentially suffer life-threatening problems involving the following:²

• Blood pressure. Blood volume doesn't increase as much as it should during pregnancy. This can affect fetal growth and well-being. The blood vessels also increase their resistance against blood flow (vasospasm), increasing blood pressure.
• Placenta. The blood vessels of the placenta don't grow deep into the uterus as they should, nor do they widen as they normally would. This makes them unable to provide normal blood flow to the fetus.
• Liver. Impaired blood circulation to the liver can cause liver damage. Liver impairment is related to the life-threatening HELLP syndrome, which requires emergency medical treatment.
• Kidneys. During a normal pregnancy, kidney function increases by up to 50%.¹⁰ When affected by preeclampsia, kidney function is usually higher than before pregnancy but not as high as necessary for a healthy pregnancy. This is called mild renal insufficiency.
• Brain. Vision impairment, persistent headaches, and seizures (eclampsia) can develop, probably in relation to reduced blood flow to or within the brain. Less than 1% of women with preeclampsia suffer one or more seizures.¹¹ Eclampsia can lead to maternal coma and fetal and maternal death. This is why women with preeclampsia are often given medicine to prevent eclampsia.
• Blood. Low platelet levels are common with preeclampsia. In rare cases, a potentially life-threatening blood-clotting and bleeding problem develops along with severe preeclampsia.⁵ This condition is called disseminated intravascular coagulation (DIC). After delivery, DIC goes away. In the meantime, blood or platelet transfusion is used to replace lost blood if necessary. For more information, see the topic Disseminated Intravascular Coagulation (DIC).

Delivery of the baby and placenta is the only "cure" for preeclampsia. If your condition becomes dangerous enough that delivery is necessary but you don't go into labor, your doctor will induce labor or surgically deliver the baby (cesarean section). Unless you have chronic high blood pressure, your blood pressure should return to normal in a few days. In severe cases, this can take 6 or more weeks.⁵

The infant

The earlier in the pregnancy that preeclampsia begins and/or the more severe the condition becomes, the greater the risk of preterm birth, which can cause newborn problems. For more information, see the topic Premature Infant.

An infant born before 37 weeks may have difficulty breathing because of immature lungs (respiratory distress syndrome). A newborn affected by preeclampsia may also be smaller than normal (intrauterine growth restriction). This is because of inadequate nutrition from poor blood flow through the placenta.

Although fetal death related to preeclampsia is a relatively rare event, the risk of fetal death is 5 times greater in preeclamptic pregnancies than in healthy pregnancies. Eclampsia further increases this risk.¹²

Risk factors for developing preeclampsia during pregnancy include:

• Chronic (ongoing) high blood pressure (hypertension). Women with chronic high blood pressure have a nearly 1-in-4 chance of developing preeclampsia. The risk is greatest when high blood pressure has been present for at least 4 years, is caused by poor kidney function, and was present during a previous pregnancy.²
• Chronic kidney disease.
• Disease of the blood vessels (vascular disease).
• Diabetes.
• High blood pressure in a past pregnancy, especially before week 34.
• Personal history of preeclampsia.
• Family history of preeclampsia, especially if either you or your partner were born from a pregnancy affected by preeclampsia.⁶
• Obesity (more than 20% over ideal weight) at the time of conception. If your weight is within this range, the higher your prepregnancy body mass index, the greater your preeclampsia risk.¹³
• Multiple pregnancy (such as twins or triplets).
• First pregnancy ever, first-time pregnancy with current partner, or first pregnancy in the past 10 years.^{3, 14}
• Age younger than 21 or older than 35.
• Molar pregnancy.
• Fetal hydrops, which is caused by Rh sensitization or an infection in the uterus.
• Pregnancy from in vitro fertilization using donor eggs.¹⁵

Women with chronic high blood pressure have an increased risk of the premature separation of the placenta from the uterine wall (placenta abruptio). This risk is further increased when:

• A mother smokes during pregnancy. Smoking is considered a cause of 15% to 25% of all placental abruption episodes.¹⁶
• Preeclampsia develops in addition to chronic high blood pressure.²

Preeclampsia probably does not cause future high blood pressure. Instead, experts think that some women who have preeclampsia also have a higher-than-normal risk of chronic high blood pressure after pregnancy or later in life.⁵

Seizures

If you have preeclampsia, it is possible that you will have an unexpected seizure (eclampsia). Eclampsia can lead to a coma and is life-threatening to both you and your fetus.

Someone must call 911 or other emergency services immediately if you are having an eclamptic seizure.

If you are pregnant and have preeclampsia, your family and friends should know how to help during a seizure.

Seek medical care immediately if you are pregnant and begin to have symptoms of preeclampsia, such as:

• Blurred vision or other vision problems.
• Frequent headaches that are becoming worse or a persistent headache that does not respond to nonprescription pain medicine.
• Pain or tenderness in your abdomen, especially in the upper right section.
• Weight gain of 2 lb (0.91 kg) or more over a 24-hour period.
• Shoulder, neck, and other upper body pain (this pain originates in the liver).

If you have mild high blood pressure or mild preeclampsia, you may not have any symptoms. It is important to see a health professional regularly throughout your pregnancy. Your blood pressure will be checked and your urine will be tested at every visit so that any abnormal rise in blood pressure or urinary protein can be easily detected.

Watchful Waiting

Symptoms such as heartburn or swelling in the legs and feet are normal during pregnancy and are not usually symptoms of preeclampsia. You can discuss these symptoms with your doctor or nurse-midwife at your next scheduled prenatal visit. However, if swelling occurs along with other symptoms of preeclampsia, contact your health professional immediately.

Who To See

If you have developed high blood pressure and preeclampsia during pregnancy, you can be treated by:

• An obstetrician.
• A family medicine doctor who is experienced in obstetric care.
• A perinatologist.
• A certified nurse-midwife supervised by an obstetrician or a perinatologist.

To prepare for your appointment, see the topic Making the Most of Your Appointment

High blood pressure (hypertension) and preeclampsia are typically detected during regular prenatal checkups. Because these conditions can get worse rapidly and can be life-threatening to you and your fetus, it's important that you have regular checkups during your pregnancy.

Prepregnancy

A prepregnancy blood pressure reading is used to:

• Screen for chronic high blood pressure (hypertension). It's important to know whether you have chronic high blood pressure before becoming pregnant, because it increases your risk of developing preeclampsia.
• Provide a baseline measurement that can be compared with later readings during pregnancy.

Routine prenatal tests

Certain tests are given at each prenatal visit to monitor for high blood pressure and preeclampsia. These include a:

• Blood pressure reading. (See considerations about blood pressure readings during pregnancy for more information.)
• Urine test for excess protein in the urine (proteinuria), a sign of preeclamptic kidney damage.
• Weight measurement. (Rapid weight gain can be an indicator of preeclamptic fluid retention.)

Tests for pregnant women considered at high-risk for preeclampsia

Additional tests may be used to monitor for signs of preeclampsia, including:

• Blood tests to check for blood abnormalities (as in HELLP syndrome) and for signs of kidney damage. (Elevated uric acid in the blood is often the earliest sign of preeclampsia.)
• Creatinine clearance test, which requires both a blood sample and a 24-hour urine collection, to assess kidney function.
• 24-hour urine collection test to assess protein in the urine.

Tests for women with preeclampsia

If results from one or more of the above tests suggest that you have preeclampsia, you and your fetus will be closely monitored throughout the remainder of your pregnancy. The type and frequency of testing depend on the severity of the preeclampsia and the time remaining until your pregnancy reaches full term (37 to 42 completed weeks). Testing is more frequent and extensive when preeclampsia is severe and the pregnancy is far from full-term (less than 36 weeks).

Tests that may be given to assess your health if you have preeclampsia include:

• A physical exam for signs and symptoms of worsening preeclampsia.
• Blood tests to check for blood abnormalities and kidney damage.
• A creatinine clearance test, which requires both blood and urine samples, to assess kidney function.

Tests for women with eclampsia

If you have a seizure (eclampsia), one or more of the following tests may be done after delivery to assess your brain function and condition:

• A computed tomography (CT) scan uses x-rays to produce detailed pictures of structures inside the body.
• Magnetic resonance imaging (MRI) uses a magnetic field and pulses of radio wave energy to provide pictures of organs and structures inside the body.
• An electroencephalogram (EEG) measures the brain's electrical activity using sensors attached to your head and connected by wires to a computer.

Tests for the fetus

If you develop high blood pressure, preeclampsia, or both, your fetus's health also will be closely monitored. The more severe your condition, the more frequent the fetal testing, ranging from once a week to daily.

Tests commonly used to monitor fetal health include:

• Electronic fetal heart monitoring (including nonstress tests), which records the fetal heart rate and the change in heart rate with fetal movement.
• Fetal ultrasound, which uses reflected sound waves to produce a computerized picture of the fetus, placenta, and uterus to check:
  • Fetal well-being and growth.
  • The condition of the placenta and the possibility of placenta abruptio.
  • The amount of amniotic fluid surrounding the fetus.

Less commonly, amniocentesis is used to check fetal well-being if preterm delivery is being considered as a treatment option. For this procedure, a needle is inserted into your abdomen to collect amniotic fluid from inside the uterus. The fluid is then checked for chemical signs that the fetus's lungs are mature.

Early Detection

Throughout your pregnancy, prenatal visits will include routine blood pressure measurements and urine tests to screen for preeclampsia.

If your blood pressure begins to rise during pregnancy, you will need close monitoring until after your baby is born. Your blood pressure may remain mildly elevated (transient hypertension), which is not considered dangerous for you or your fetus. However, it can become dangerous if it turns out to be a sign of preeclampsia or if it progresses to more severe high blood pressure (hypertension).

High blood pressure (hypertension) during pregnancy

If you have high blood pressure during your pregnancy, your treatment will include:

• Close monitoring by a doctor for signs of preeclampsia.

• A balanced diet, mild aerobic exercise, and possibly blood pressure medicine. Management with a balanced diet and mild aerobic exercise (such as walking) may be sufficient treatment for high blood pressure during pregnancy. Some women with ongoing (chronic) high blood pressure stay on antihypertensive medicine but are prescribed a lower dose during pregnancy if their blood pressure improves.

Mild high blood pressure in pregnancy usually only requires close monitoring. If you have high blood pressure that is rapidly increasing or has reached moderately high levels (above 140/105 mm Hg, or millimeters of mercury), you may be treated with blood pressure medicine.

Severe high blood pressure (higher than 160 mm Hg systolic or 110 mm Hg diastolic) can result in poor fetal growth (intrauterine growth restriction) and is likely to be treated with an antihypertensive medicine.

Some high blood pressure medicines are dangerous during pregnancy. If you are taking an angiotensin-converting enzyme (ACE) inhibitor for chronic high blood pressure before pregnancy, you will need to change to a medicine that is safe for your developing fetus. Studies show that ACE inhibitors can cause serious birth defects.¹⁷ Examples of ACE inhibitors include benazepril (Lotensin), captopril (Capoten), and enalapril (Vasotec). Discuss this with your health professional before becoming pregnant (or as soon as you learn you are pregnant). Your doctor or nurse-midwife will likely recommend that you stop using your medicine for the first trimester, because your blood pressure should naturally lower during early pregnancy.

Preeclampsia and eclampsia

If you show any signs of preeclampsia, you will be closely monitored, either with frequent office visits or in the hospital. The goal of treatment is to prevent preeclampsia from becoming life-threatening to you and your fetus while prolonging the pregnancy long enough for your fetus to be mature and healthy at birth.

Your treatment will last for the rest of your pregnancy, your delivery, and your first postpartum weeks and will depend on how severe your condition is. Treatment options include an anticonvulsant medicine; blood pressure medicine if your blood pressure is dangerously high; and delivery, which is the only known "cure" for preeclampsia.

• For mild preeclampsia that is not rapidly getting worse, you may only have to reduce your level of activity, monitor how you feel, and have frequent office visits and testing.
• For moderate or severe preeclampsia, or for preeclampsia that is rapidly getting worse, you will require hospitalization, where expectant management typically includes bed rest, medicine, and close monitoring of you and your fetus. Severe preeclampsia or an eclamptic seizure is treated with magnesium sulfate. This medicine can stop a seizure and can prevent seizures. If you are near delivery or have severe preeclampsia, your doctor will plan to deliver your baby as soon as possible.
• If your condition becomes life-threatening to you or your fetus, magnesium sulfate to prevent seizure and delivery are the only treatment options. If you are less than 34 weeks pregnant and a 24- to 48-hour delay is possible, you will likely be given antenatal corticosteroids to speed up fetal lung development before delivery.

After childbirth

If you have moderate to severe preeclampsia, your risk of seizures (eclampsia) continues for the first 24 to 48 hours after childbirth (in very rare cases, seizures are reported later in the postpartum period). You will therefore continue magnesium sulfate for 24 hours after delivery.⁵

Unless you have chronic high blood pressure, your blood pressure is likely to return to normal a few days after delivery. This can, however, take 6 weeks or more—some women still have high blood pressure 6 weeks after childbirth yet return to normal levels over the long term. If your diastolic blood pressure reading (the lower, second number) is still over 100 mm Hg when you leave the hospital, you will likely be prescribed a high blood pressure medicine.⁵ You will then have regular checkups with your health professional to monitor your recovery.

Taking high blood pressure medicine while breast-feeding

There are several commonly used high blood pressure medicines that have no reported effects on the breast-feeding baby. These medicines include labetalol and propranolol, which are most commonly recommended, as well as hydralazine and methyldopa. Nadolol, metoprolol, and nifedipine are detectable in mothers' milk, but they have no known effects on the breast-feeding baby.¹⁸

What To Think About

To prepare for a talk with your doctor or nurse-midwife about your condition, see questions to ask your doctor about high blood pressure and pregnancy.

Anticonvulsant medicine

Moderate or severe preeclampsia or an eclamptic seizure is treated with intravenous magnesium sulfate to prevent seizures. For mild preeclampsia, magnesium sulfate is sometimes used to prevent seizures (eclampsia). Research has not yet clarified whether magnesium sulfate is beneficial or needed for the treatment of mild preeclampsia.^{2, 19}

High blood pressure medicine

Lowering blood pressure with medicine:

• Does not prevent preeclampsia from getting worse, because high blood pressure is only a symptom of the condition, not a cause.
• Can reduce blood flow to the placenta if blood pressure is lowered too rapidly, causing problems for the fetus. Medicine is therefore reserved for preventing severely high blood pressure levels that are potentially life-threatening to you or your fetus.

Delivery

A vaginal delivery is usually safest for the mother and is attempted first if she and the baby are both stable. If preeclampsia is rapidly getting worse or fetal monitoring suggests that the baby cannot safely handle labor contractions, a cesarean section (C-section) delivery is needed.

Ongoing issues

One large study suggests that women who have had preeclampsia or other problems related to the placenta also have a higher chance of getting disease of the heart or blood vessels (cardiovascular disease) at an early age.²⁰ Preeclampsia does not cause the problems, but may be an early warning sign. Healthy habits such as regular exercise, eating a healthy diet, and monitoring cholesterol and blood pressure may help prevent future illness. If you have had preeclampsia, talk to your doctor about ways to prevent cardiovascular problems.

If you have chronic high blood pressure (hypertension), you can lower your blood pressure before pregnancy by exercising, eating a diet low in sodium and rich in fruits and vegetables, and staying at a healthy weight. Lowering your blood pressure reduces your risk of preeclampsia.

When you are pregnant, regular checkups are key to early detection and treatment. Prompt treatment is vital to preventing the development of severe and possibly life-threatening preeclampsia.

Recent preeclampsia research suggests that calcium supplements and low-dose aspirin offer a preventive benefit, especially for high-risk women.

Calcium supplements may reduce the risk of developing preeclampsia and the risk of having a low-birth-weight baby, particularly among high-risk women who normally don't get enough calcium.¹ Taking a calcium supplement may also lower the risk of moving from mild to severe preeclampsia.²¹ Other experts have found that there is no benefit from taking calcium.⁵

All pregnant women can generally benefit from taking the U.S. Food and Drug Administration's recommended daily allowance of 1200 mg of calcium per day.

Low-dose aspirin (antiplatelet) therapy may be a moderately effective preventive treatment for women at risk of developing preeclampsia. A review of studies involving over 36,000 pregnant women showed that taking antiplatelet medicine lowered their risk of preeclampsia, preterm birth related to preeclampsia, and fetal or newborn death related to preeclampsia.²² Although some experts question how effective low-dose aspirin is, others assert that high-risk women who take it regularly as directed do significantly lower their preeclampsia risk.²³ Talk to your doctor or nurse-midwife about whether this treatment is right for you.

Research shows that taking vitamin C or vitamin E supplements does not help prevent preeclampsia.^{24, 25}

High blood pressure

If you have ongoing (chronic) high blood pressure and are taking blood pressure medicine, talk to your health professional before becoming pregnant (or as soon as you learn you are pregnant). Some high blood pressure medicines are dangerous to your fetus.

If you have high blood pressure during pregnancy, take steps that will help control your blood pressure:

• Go to all of your prenatal checkups. It is important to monitor your blood pressure because a dangerous increase in blood pressure can occur without symptoms. You may also want to keep track of your blood pressure readings at home.
• If you smoke, quit smoking. This helps decrease your blood pressure and improve your fetus's growth and health.
• Do not gain an excessive amount of weight during your pregnancy. Talk to your health professional about how much is healthy for you to gain.
• Get regular mild exercise during pregnancy. Walking or swimming several times weekly can be healthy for you and your developing fetus. Because high blood pressure may reduce the oxygen supply to the placenta and fetus, the National Institutes of Health recommends avoiding vigorous exercise if you have high blood pressure during pregnancy.²
• Reduce stress. Find time to relax, especially if you continue to work, are parenting small children at home, and/or have a hectic schedule.

By following general guidelines for a healthy pregnancy, you can help optimize your own and your baby's overall health and ensure that you are both in the best possible shape for handling the challenges of pregnancy, delivery, and recovery.

Expectant management for preeclampsia

If you develop signs of preeclampsia early in pregnancy, your doctor or nurse-midwife may prescribe something called expectant management at home, possibly for many weeks. This may mean you are advised to stop working, reduce your activity level, or possibly spend a lot of time resting (partial bed rest). Although partial bed rest is considered reasonable treatment for preeclampsia, its effectiveness is not proven for treating mild preeclampsia.²⁶ It is known, however, that strict bed rest for 3 days or more increases the risk of developing a blood clot in the legs or lungs (from about 1 in 1,000 to as high as 16 in 1,000).²⁷

Whether you are required to reduce your activity or have partial bed rest, expectant management severely limits your ability to work, remain active, take care of children, and fulfill other responsibilities. It may be helpful to follow some tips for dealing with bed rest.

You may be required to monitor your own condition on a daily basis. If so, you or another person (such as a trained family member or a visiting nurse) will:

• Monitor your blood pressure at home.
• Check your urine for protein.
• Check your weight. Before checking your weight, you should empty your bladder, take off your shoes, and wear about the same amount of clothing each time.
• Monitor fetal movements.

Monitoring your blood pressure at home

Keep a written record of your results, including the dates and times you checked. Take this record with you when you visit your doctor or nurse-midwife.

Medicine for preeclampsia and high blood pressure during pregnancy may be used to:

• Control high blood pressure. Lowering high blood pressure does not prevent preeclampsia from getting worse, because high blood pressure is only a symptom of the condition, not a cause. High blood pressure medicine is usually not used unless a pregnant woman's diastolic blood pressure (the second number) reaches levels of about 105 mm Hg (millimeters of mercury) and above.⁵ Expectant management is the preferred treatment for mild high blood pressure during pregnancy.
• Prevent seizures. Magnesium sulfate is usually started before delivery and continued for 24 hours after delivery for women with pregnancy-related seizures (eclampsia) and those with moderate to severe preeclampsia.
• Speed up fetal lung development. When possible, a corticosteroid (betamethasone or dexamethasone) is given to the mother prior to a premature birth (up to 34 weeks of gestation). This medicine matures the fetus's lungs over a 24-hour period, which lowers the risk of breathing problems after birth.

After childbirth: Taking high blood pressure medicine while breast-feeding

There are several commonly used high blood pressure medicines that have no reported effects on the breast-feeding baby. These medicines include labetalol and propranolol, which are most commonly recommended, as well as hydralazine and methyldopa. Nadolol, metoprolol, and nifedipine are detectable in mothers' milk, but they have no known effects on the breast-feeding baby.¹⁸

Medication Choices

High blood pressure medicines commonly used during pregnancy include:

• Methyldopa (a first-choice oral medicine for controlling high blood pressure during a pregnancy).
• Hydralazine (a first- or second-choice intravenous medicine for quickly lowering severely high blood pressure during pregnancy).
• Labetalol (a first- or second-choice intravenous medicine for quickly lowering severely high blood pressure in the hospital, and also considered a first- or second-choice oral medicine for controlling high blood pressure during pregnancy).
• Nifedipine (a first- or second-choice oral medicine for controlling high blood pressure during pregnancy).

Magnesium sulfate is considered the safest and most effective anticonvulsant for preventing eclampsia (seizures) during pregnancy.²

Antenatal corticosteroid medicines include betamethasone and dexamethasone. Research suggests that corticosteroids are the single most effective treatment for preventing complications in preterm newborns.²⁸

What To Think About

There is currently not enough medical evidence to show which high blood pressure medicine is most effective for use during pregnancy. But it does seem clear that 2 drugs—diazoxide and ketaserin—are the least reliable for use during pregnancy.²⁹ Although the above-mentioned medicines are widely used, further large studies are needed.

Some high blood pressure medicines are dangerous during pregnancy. If you are taking an angiotensin-converting enzyme (ACE) inhibitor for chronic high blood pressure before pregnancy, you will need to change to a medicine that is safe for your developing fetus. Studies show that ACE inhibitors can cause serious birth defects.¹⁷ Discuss this with your health professional before becoming pregnant (or as soon as you learn you are pregnant).

Lowering blood pressure too much or too fast can reduce blood flow to the placenta, causing problems for the fetus. Medicine is therefore reserved for preventing severely high blood pressure levels that are potentially life-threatening to you or your fetus. Your doctor or nurse-midwife will likely recommend that you stop using your medicine for the first trimester, because your blood pressure will naturally lower during early pregnancy.

There is no surgical treatment for high blood pressure during pregnancy or for preeclampsia.

Surgical cesarean section delivery is used when:

• A rapid delivery is medically needed for the mother's or fetus's well-being or survival.
• Induction of labor has not been successful, usually within a 24-hour period.
• There are medical reasons, such as placenta previa, that make vaginal delivery dangerous.

For more information, see the topic Cesarean Section.

Delivery

The main treatment for severe preeclampsia is stabilizing the condition (preventing seizures with the anticonvulsant medicine magnesium sulfate and controlling high blood pressure) and delivering the baby. If you have severe preeclampsia or you have mild to moderate preeclampsia and are close to your due date, your baby will be delivered. Vaginal delivery is preferred to cesarean delivery.

Expectant management

Your condition may be treated with expectant management (bed rest) either at home or in the hospital. The purpose of expectant management is to allow more time for fetal development, for the cervix to become ready for a vaginal delivery, or both.

Social support

Reduced activity and worry are difficult parts of having preeclampsia. Conversation with women who are or have been in the same situation is often helpful. See the Other Places to Get Help section of this topic for more information.

Organizations

• Cesarean Section
• High Blood Pressure (Hypertension)
• Premature Infant
• Preterm Labor

Citations

1. Duley L (2005). Pre-eclampsia and hypertension, search date November 2004. Online version of Clinical Evidence (14): 1776–1790.

2. National High Blood Pressure Education Working Group (2000). Report on High Blood Pressure in Pregnancy (NIH Publication No. 00–3029). Washington, DC: National Institutes of Health.

3. Roberts JM, et al. (2003). Summary of the NHLBI working group on research on hypertension during pregnancy. Hypertension in Pregnancy, 22(2): 109–127.

4. Cunningham FG, et al. (2005). Hypertensive disorders in pregnancy. In Williams Obstetrics, 22nd ed., pp. 761–808. New York: McGraw-Hill.

5. Roberts JM (2004). Pregnancy-related hypertension. In RK Creasy, R Resnik, eds., Maternal-Fetal Medicine, 5th ed., pp. 859–899. Philadelphia: Saunders.

6. Esplin MS, et al. (2001). Paternal and maternal components of the predisposition to preeclampsia. New England Journal of Medicine, 344(12): 867–872.

7. Solomon CG, Seely EW (2004). Preeclampsia—Searching for the cause. New England Journal of Medicine, 350(7): 641–642.

8. Roberts JM, Cooper DW (2001). Pathogenesis and genetics of pre-eclampsia. Lancet, 357(9249): 53–56.

9. Stone JH (1998). HELLP syndrome: Hemolysis, elevated liver enzymes, and low platelets. JAMA, 280(6): 559–562.

10. Cunningham FG, et al. (2005). Maternal physiology. In Williams Obstetrics, 22nd ed., pp. 122–150. New York: McGraw-Hill.

11. Witlin AG, Sibai BM (1998). Magnesium sulfate therapy in preeclampsia and eclampsia. Obstetrics and Gynecology, 92(5): 883–889.

12. Perloff D (1998). Hypertension and pregnancy-related hypertension. Cardiology Clinics, 16(1): 79–101.

13. O'Brien TE, et al. (2003). Maternal body mass index and the risk of preeclampsia: A systematic overview. Epidemiology, 14(3): 368–374.

14. Skjaerven R, et al. (2002). The interval between pregnancies and the risk of preeclampsia. New England Journal of Medicine, 346(1): 33–38.

15. Wiggins DA, Main E (2005). Outcomes of pregnancies achieved by donor egg in vitro fertilization—A comparison with standard in vitro fertilization pregnancies. American Journal of Obstetrics and Gynecology, 192(6): 2002–2008.

16. Ananth CV, et al. (1999). Incidence of placental abruption in relation to cigarette smoking and hypertensive disorders during pregnancy: A meta-analysis of observational studies. Obstetrics and Gynecology, 93(4): 622–628.

17. Cooper WO, et al. (2006). Major congenital malformations after first-trimester exposure to ACE inhibitors. New England Journal of Medicine, 354(23): 2443–2451.

18. American Academy of Pediatrics (2001). The transfer of drugs and other chemicals into human milk. Pediatrics, 108(3): 776–789.

19. Sibai BM (2004). Magnesium sulfate prophylaxis in preeclampsia: Lessons learned from recent trials. American Journal of Obstetrics and Gynecology, 190(6): 1520–1526.

20. Ray JG, et al. (2005). Cardiovascular health after maternal placental syndromes (CHAMPS): Population-based retrospective cohort study. Lancet, 366(9499): 1797–1803.

21. Villar J, et al. (2006). World Health Organization randomized trial of calcium supplementation among low calcium intake pregnant women. American Journal of Obstetrics and Gynecology, 194(3): 639–649.

22. Duley L, et al. (2006). Antiplatelet agents for preventing pre-eclampsia and its complications. Cochrane Database of Systematic Reviews (1). Oxford: Update Software.

23. Coomarasamy A, et al. (2003). Aspirin for prevention of preeclampsia in women with historical risk factors: A systematic review. Obstetrics and Gynecology, 101(6): 1319–1332.

24. Poston L, et al. (2006). Vitamin C and vitamin E in pregnant women at risk for pre-eclampsia (VIP trial): Randomised placebo-controlled trial. Lancet, 367(9517): 1145–1154.

25. Rumbold AR, et al. (2006). Vitamins C and E and the risks of preeclampsia and perinatal complications. New England Journal of Medicine, 354(17): 1796–1806.

26. Sibai BM (2003). Diagnosis and management of gestational hypertension and preeclampsia. Obstetrics and Gynecology, 102(1): 191–192.

27. Kovacevich GJ, et al. (2000). The prevalence of thromboembolic events among women with extended bed rest prescribed as part of the treatment for premature labor or preterm rupture of membranes. American Journal of Obstetrics and Gynecology, 182(5): 1089–92.

28. Sawdy RJ, Bennett PR (1999). Recent advances in the therapeutic management of preterm labour. Current Opinion in Obstetrics and Gynecology, 11(2): 131–139.

29. Duley L, Henderson-Smart DJ (2006). Drugs for treatment of very high blood pressure during pregnancy. Cochrane Database of Systematic Reviews (1). Oxford: Update Software.

Other Works Consulted

• American College of Obstetricians and Gynecologists (2002). Diagnosis and management of preeclampsia and eclampsia. ACOG Practice Bulletin No. 33. Obstetrics and Gynecology, 99(1): 159–167.

• Duley L, et al. (2001). Antiplatelet drugs for prevention of pre-eclampsia and its consequences: Systemic review. BMJ, 322(7282): 329–333.

Author:	Shannon Erstad, MBA/MPH	Last Updated November 22, 2006
Medical Review:	Joy Melnikow, MD, MPH - Family Medicine William Gilbert, MD - Perinatology
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