Preclampsia Overview

Preeclampsia occurs in about one out of every 20 pregnancies in the United States.

Preeclampsia is a unique form of hypertension that occurs only during pregnancy. In developed countries, preeclampsia occurs in about 5% pregnancies. It usually develops after the 20th week of gestation and is characterized by the onset of hypertension and proteinuria (protein in the urine).Edema (excessive swelling)-typically in the hands and face-may also be present.. Table 1 summarizes the factors your doctor considers when diagnosing preeclampsia. As part of your standard prenatal care, your doctor assesses your blood pressure and the level of protein in your urine. These tests are also the most definitive means of diagnosing preeclampsia.

Chronic hypertension is a hypertensive disorder present before pregnancy. One of the most common medical complications of pregnancy, chronic hypertension may be diagnosed:

• if you have hypertension before you become pregnant; or
• if your blood pressure before your 20th week of pregnancy is above 140 mmHg systolic or 90 mmHg diastolic on two occasions at least six hours apart.

Although chronic hypertension increases the risk for several conditions specific to pregnancy, most women with mild to moderate chronic hypertension do not experience complications. In fact, blood pressure control actually improves for the majority of pregnant women with underlying chronic hypertension. In some cases, however, chronic hypertension worsens during pregnancy. Approximately 15 to 25% of women with chronic hypertension develop superimposed preeclampsia, which greatly increases the risk of complications for the mother and her baby. The risk of superimposed preeclampsia is greatest for those mothers with severe chronic hypertension or chronic hypertension complicated by kidney disease.

Conditions associated with superimposed preeclampsia include:

• hypertensive encephalopathy (swelling of the cerebrum of the brain);
• heart failure;
• worsening of kidney problems;
• placental abruption (separation of the placenta from the uterus);
• fetal growth restriction;
• premature delivery; and
• increased risk of fetal death.

Fetal Growth Restriction

Fetal growth restriction is a major risk factor of chronic hypertension. Hypertension may restrict blood flow to the placenta, depriving the fetus of nutrients and oxygen required for normal growth. Women with chronic hypertension are monitored closely throughout their pregnancies for signs of abnormal fetal growth.

Preeclampsia affects many of the body's organs and causes various symptoms that range from mild to severe. Common symptoms associated with preeclampsia are listed in Table 2.

Placental Abruption

Placental abruption (separation of the placenta from the uterus) is another risk factor of chronic hypertension. Abruption causes bleeding between the uterus and the placenta, and can lead to maternal anemia, dangerously low blood pressure in the mother, and abnormalities in maternal blood clotting factors. In 50 to 85% of severe cases, this decrease in blood flow results in fetal death.

Who Is at a Higher Risk for Chronic Hypertension?

Chronic hypertension is increased ten-fold in obese, pregnant women. These women are also at increased risk for superimposed preeclampsia.

Hypertensive disease in pregnancy is most common in women who are older, have diabetes, or are obese. Heredity also contributes to the development of hypertension; frequently, many family members are hypertensive. Racial factors are also significant-hypertension is more common among African Americans and Mexican Americans.

Women with mild preeclampsia are unlikely to have any signs or symptoms other than mildly elevated blood pressure and proteinuria. Distinguishing between mild and severe preeclampsia is important for identifying women who are at greater risk for developing eclampsia. However, at any time mild preeclampsia can progress rapidly to severe, which is more likely to cause complications for mother and baby.

HELLP Syndrome

The HELLP syndrome is a variant of severe preeclampsia. It is characterized by:

• hemolysis (destruction of red blood cells);
• elevated liver enzymes (indicative of liver damage); and
• low blood platelet levels (indicative of impaired blood clotting, which can cause major problems during and after labor).

This condition complicates 10 to 20% of severe preeclampsia and eclampsia cases. Most commonly, it develops before delivery, but it can occur during or after delivery.

Women with HELLP syndrome often complain of pain in the upper-right quadrant of the abdomen, nausea, vomiting, and malaise (a general unwell feeling). Some women experience high blood pressure and/or proteinuria.

If you have HELLP syndrome, both you and your baby are at high risk for complications. You may require blood and blood product transfusion. If you develop kidney failure, you may require dialysis (an artificial means of filtering blood). There is a risk of bleeding in your liver or brain. Because these problems are so serious, your baby is delivered (preferably vaginally, but through cesarean section if necessary) usually within 48 hours or earlier of diagnosis, depending how close to term you are, on the well-being of your baby, or how severely the disease affects you. Therefore, your baby may be born prematurely.

Otherwise, the treatment for HELLP syndrome is usually similar to that of severe preeclampsia.

Severe Preeclampsia

Whereas mild preeclampsia may not cause obvious symptoms, severe preeclampsia is marked by the abnormalities and symptoms listed in Table 2, including headache, abdominal pain, changes in eyesight, and general discomfort. Women with severe preeclampsia are at increased risk of developing full-blown eclampsia ( preeclampsia with seizure activity).

What Causes Chronic Hypertension?

There are many causes of hypertension in pregnancy. Essential hypertension (hypertension without a known cause) accounts for 90% of cases. Other underlying causes include kidney disease, Cushing syndrome (high levels of cortisol which lead to hypertension), thyroid disease, and connective-tissue disorders. If you are diagnosed with chronic hypertension during the first half of pregnancy, your doctor reviews your family history and performs physical examinations to determine the underlying cause of your disorder.

This HealthMap discusses the diagnosis and management of chronic hypertension during pregnancy, covering both mild cases with few complications and more severe cases exacerbated by pregnancy.

What Are the Causes of Preeclampsia?

The exact causes of preeclampsia are unknown. Growing evidence suggests, however, that damage to the mother's vascular endothelial tissue (the tissue that lines blood vessels) may trigger the abnormal functions and symptoms that develop in preeclampsia.

Are Some Women More Susceptible than Others?

Preeclampsia occurs most often in young women during their first pregnancies. However, it is also common among women over age 35 who have been pregnant before, women who have had preeclampsia in a prior pregnancy, and women carrying more than one baby. If your sister or mother had preeclampsia, you may be at higher risk. Certain illnesses can also make you more susceptible to developing preeclampsia.

Who's at Risk?

Preeclampsia affects about one of every 20 pregnancies in the U. S. and other developed countries. Risk factors include:

• first pregnancy (6 to 8 times more susceptible than women with previous pregnancies);
• being pregnant with multiple babies (2 to 5 times more susceptible);
• women who have had severe preeclampsia or eclampsia (50 to 65% more susceptible);
• women whose sisters or mothers had preeclampsia (205% more susceptible; 4-5 times more likely than the general population);
• pregnancy after age 35 in women who have been pregnant before;
• chronic hypertension, kidney disease, thyroid disease, or diabetes;pregnancy after age 35 in women who have been pregnant before;
• hydatidiform mole (an abnormal pregnancy resulting in a mass of cysts that resemble a bunch of grapes); and
• collagen vascular disease, or antiphospholipid syndrome.

Although the complications of severe preeclampsia can be life threatening, they are relatively rare. When they do arise, they can be managed effectively. In fact, symptoms of preeclampsia usually resolve soon after delivery. Even if you develop kidney failure and require dialysis, your kidney function will most likely return to normal within six weeks.

Early Detection and Being an Active Patient

To protect yourself against potential complications, you should be screened for the characteristic signs of preeclampsia-hypertension and proteinuria. These signs should be detected as early as possible. You should initiate prenatal care as soon as you know you are pregnant, and you should not miss any scheduled appointments.

If you have had preeclampsia in the past, it does not mean that you should not get pregnant again. But, you should talk to your doctor first. You will need to be followed closely during your pregnancy and monitored frequently for signs and symptoms of preeclampsia should it develop again..

This HealthMap guides you through the steps you and your doctor may take after you have been diagnosed with preeclampsia. Your treatment varies according to the severity of the disorder, how close you are to term, whether you have any other health problems, and other possible factors. Learning about preeclampsia helps you actively participate in your treatment. When you see your doctor, raise any questions and concerns you may have. You may find it helpful to write questions down before you see your doctor or to take notes during your visits.