Preeclampsia: Causes, Symptoms, Diagnosis, and Treatment
January 30, 20190884


What is Preeclampsia?

Preeclampsia was once referred to as toxemia of pregnancy.  Preeclampsia was called toxemia

because it was thought that toxins, or poisons, were the cause of the condition.  Until the late 1800s, women with “toxemia” were admitted to hospitals for treatment.  Treatment involved purging (inducing vomiting) or bloodletting (sometimes with leeches) in an attempt to remove the offending toxins and re-balance the body’s fluids.1

We do not know enough about preeclampsia even today, but we have come a long way since the days of bloodletting.  Preeclampsia was redefined as a blood pressure condition of pregnancy (rather than a toxic condition) after the advent of the blood pressure cuff in the late 1800s. Scientific advances in the 1900s helped us learn more about the possible origins of preeclampsia in pregnancy.We now know that preeclampsia is not caused by toxins or poisons in the body.  We have stopped referring to preeclampsia as toxemia in pregnancy.  We know that the application of leeches is not going to cure preeclampsia. However, we are still waiting to discover a cause, and a cure, for preeclampsia.

What exactly is preeclampsia?  Preeclampsia is one of several blood pressure conditions of pregnancy.

The blood pressure conditions associated with pregnancy include:

  • Chronic hypertension is a high blood pressure condition defined by blood pressure that is over 140/90. Chronic hypertension is high blood pressure that exists outside of pregnancy.  A woman has chronic hypertension if she has high blood pressure prior to becoming pregnant.
  • Gestational hypertension is a high blood pressure condition (with blood pressure that is over 140/90) that starts during the second half of pregnancy. A woman who had normal blood pressure in the first half of pregnancy, but develops high blood pressure during the second half of pregnancy and has no preeclampsia signs or symptoms, is diagnosed as having gestational hypertension.
  • Preeclampsia, without severe features, was once referred to as “mild preeclampsia.” Preeclampsia is a condition that can only occur during the second half of pregnancy, or in the weeks immediately after delivery.  If, after 20 weeks of pregnancy, a woman’s blood pressure is between 140/90 and 160/110, and she has protein in her urine, or evidence that there is kidney, liver or other organ damage, and has no other preeclampsia signs or symptoms, she is diagnosed with “preeclampsia without severe features.”
  • Preeclampsia with severe features, once called “severe preeclampsia,” also occurs only during pregnancy. If, during the second half of pregnancy, a woman’s blood pressure climbs over 160/110, and she has protein in her urine, or a constellation of other preeclampsia signs and symptoms, she is diagnosed as having “preeclampsia with severe features.”
  • Eclampsia occurs when preeclampsia is accompanied by seizures.
  • Preeclampsia superimposed on chronic hypertension is preeclampsia that occurs in a pregnant woman who has preexisting high blood pressure, or, chronic hypertension.2


It is important to correctly differentiate these blood pressure conditions of pregnancy.  The proper diagnosis guides treatment, leading to the best outcomes for the pregnant woman and her baby.  Preeclampsia is a serious and complex condition. Without proper diagnosis and treatment, preeclampsia can be life threatening. In the United States alone, one in every 100,000 pregnant women will die from complications of preeclampsia. For every 10,000 preeclamptic pregnancies, more than six women will die.3

  • Preeclampsia Causes

Despite a tremendous amount of research, we do not know exactly what causes preeclampsia.  Likely, many factors go into the development of preeclampsia.  There are some sound theories about what causes preeclampsia, though nothing has yet been confirmed.  Theories of preeclampsia causes include:

  • Placental issues. During the earliest days of pregnancy, the embryo implants into the uterus.  From the embryo, the placenta (also known as the afterbirth) develops and attaches to the inside wall of the uterus.  The placenta is important because it is the organ through which the baby receives oxygen and nutrition. We think that abnormalities in the way the placenta implants into the uterus might cause preeclampsia.
  • Maternal immune system issues. During pregnancy, the immune system is somewhat weakened.  The weakening of the immune system protects the pregnancy from being recognized by the body as “foreign,” or abnormal.  This protective mechanism prevents the immune system from attacking the pregnancy.  It is possible that problems with the way the woman’s immune system responds to the genetic tissue of the pregnancy may cause preeclampsia.
  • Poor maternal adaptation to pregnancy. Pregnancy effects almost every system of the body.  Women build up extra blood volume during pregnancy in anticipation of the blood that is lost at the time of delivery, and in the days and weeks thereafter.  The heart has to work harder to pump the extra blood volume.  Researchers theorize that some women don’t adapt well to these changes of normal pregnancy and this maladaptation causes preeclampsia.
  • We know that women who have a mother or sister who had preeclampsia is at higher risk for developing preeclampsia herself. There are theories that certain genetic factors increase the risk of preeclampsia.4
  • Preeclampsia Symptoms

The symptoms of preeclampsia are the same regardless of gestational age (the number of weeks of pregnancy).  The symptoms of preeclampsia are the same at 24 weeks of pregnancy, for example as they are at 39 weeks of pregnancy.  Many women with preeclampsia have no symptoms.

We do know that, as the severity of symptoms increases, the risks of progressing disease increase as well.  The presence of any of these symptoms is an indication to contact your health care provider immediately.



Some of the hallmark symptoms of pregnancy include:

  • A preeclampsia headache is a serious symptom.  Headaches in pregnancy that do not resolve after taking Tylenol or other analgesic (pain reliever) may indicate cerebral edema (swelling of the brain).  Preeclampsia headaches are considered immediate risk factors for seizure and stroke.
  • Visual changes. Preeclampsia symptoms include seeing spots, flashing lights or “floaters” that you did not have before.  These visual changes, like a preeclampsia headache, are also serious preeclampsia symptoms and may indicate impending seizure or stroke.
  • In rare cases, women with preeclampsia experience partial or full vision loss.  When full or partial blindness does occur, it is considered to be temporary.  Vision usually returns once the preeclampsia has resolved.
  • Abdominal pain. Pain in the abdomen is concerning, particularly if the pain is in the area under the bottom of the ribs on the right side.   This right-sided abdominal pain may indicate pressure of the liver swelling against the liver capsule.  Swelling of the liver may precede liver rupture, a life-threatening condition that requires a liver transplant for survival.
  • Nausea and vomiting. Many women have nausea and vomiting during the first trimester (first 12 weeks) of pregnancy.  Nausea and vomiting that occurs during this early part of pregnancy is not related to preeclampsia.  Having nausea and vomiting in early pregnancy does not mean that a woman will have preeclampsia later in pregnancy.  Early pregnancy nausea and vomiting is a response to increasing levels of pregnancy hormone.  Persistent nausea and vomiting that occurs in the second half of pregnancy (after the 20 week mark), may be a symptom of preeclampsia.
  • Edema (swelling). Many pregnant women will experience edema during pregnancy. Normal pregnancy-related swelling is usually better in the morning, and becomes more significant during the course of the day.  Women who have preeclampsia swelling have little relief from edema even after being off of their feet for several hours.
  • Diagnosis of Preeclampsia

High blood pressure is the hallmark preeclampsia sign.  Tests are indicated when your health care provider notes a blood pressure of more than 140/90 in a pregnant woman.  This set of blood and urine tests is commonly referred to as “preeclampsia labs.”  Preeclampsia labs help your health care provider make the proper diagnosis.



Testing may include:

  • Checking for protein in the urine. Urine protein can be assessed from a 24 hour urine collection.  Quicker results can be obtained with a single specimen urine test called the protein to creatinine ratio (P:C).  A 24 hour urine test with greater than or equal to 300 of protein is considered abnormal.  A protein to creatinine ratio that is greater than or equal to three is abnormal.  High levels of protein in the urine, also called proteinuria, indicate problems with kidney function.  In the presence of increased blood pressure as described above, proteinuria makes a diagnosis of preeclampsia.
  • Checking liver enzymes levels. A blood test can be done to check the levels of enzymes called aspartate transaminase (AST) and alanine transaminase (ALT).  These tests reveal how well the liver is functioning.  Abnormally high values may indicate restricted blood flow in the liver.
  • Checking platelet levels. A blood test can be done to evaluate platelet levels.  Platelets are a component of blood that facilitate blood clotting.  A low platelet count is theoretically caused by the body’s increased use and/or increased destruction of platelets.
  • Checking the hemoglobin and hematocrit. A blood test can be done to check the hemoglobin and hematocrit.  The hemoglobin and hematocrit are measures of red cells in the blood.  The levels of hemoglobin and hematocrit may increase due to fluid volume constriction.
  • Checking uric acid and LDH (lactate dehydrogenase) levels. Blood tests can be done to check uric acid and LDH levels.  Uric acid levels in the blood increase when the kidneys are unable to secrete breakdown products of blood cells. LDH increases when there is increased breakdown of cells, particularly from the skeletal muscle, kidneys, liver, brain, lungs and heart.  The value of uric acid and LDH levels in diagnosing preeclampsia is under debate.
  • Checking BUN (blood urea nitrogen) and creatinine. A blood test can be done to check these measures of kidney function.
  • Checking fetal growth. An ultrasound can be done to measure how well the baby is growing.  It can also measure the blood flow through the placenta.  The baby’s growth and blood flow through the placenta are indications of how well the placenta is functioning.4,5,6
  • Treatment for Preeclampsia

The only cure for preeclampsia is delivery of the baby.  It is easy to make a decision to deliver a baby when the pregnancy is full-term.  The decision making process is more difficult when a pregnancy is preterm and complicated by preeclampsia.

The decision of when to deliver your baby is usually made depending on the severity of your preeclampsia and the number of weeks you are pregnant.  A maternal-fetal medicine specialist should be involved in the care of any women who has preeclampsia before the pregnancy is full-term.

It is possible to treat some of the conditions of preeclampsia, such as severely high blood pressure.  It is also possible to prevent complications of preeclampsia, such as seizure and stroke.  It is important to remember that none of these treat the preeclampsia itself, and that preeclampsia will not resolve until the baby is delivered.



Treatments may include:

  • Rest on your left side.
  • An intravenous infusion of magnesium sulfate may help to prevent seizures.
  • Anti-hypertensive (blood pressure lowering) medications such as labetalol and hydralazine may help to prevent stroke.
  • Lasix (a diuretic) may help to prevent or treat pulmonary edema.
  • Preeclampsia Prevention

Preeclampsia remains somewhat of a medical mystery.  We do not know exactly what causes preeclampsia, and we do not know how to prevent it.


We do know that some women are at higher risk for developing preeclampsia than others.  For these higher-risk women, taking low dose aspirin (81mg, or one baby aspirin) daily may help prevent preeclampsia.  We don’t think that aspirin is helpful for low risk women, and aspirin does have potential risks including stomach irritation and bleeding.

Do not take aspirin during pregnancy unless expressly instructed to by your health care provider.

The best way to prevent preeclampsia during pregnancy is to reduce risk factors before becoming pregnant.  If you have high blood pressure and/or diabetes before becoming pregnant, getting them under tight control could help to prevent preeclampsia.  Losing weight, or maintaining a healthy weight prior to pregnancy could reduce your risk of preeclampsia.

Getting regular exercise and a eating a diet high in fresh fruits and vegetables, whole grains and lean proteins, both before and during pregnancy, may reduce your preeclampsia risk.  Statins (cholesterol lowering medications) are showing some promise in reducing preeclampsia risk, but are not currently used clinically for the prevention of preeclampsia.

Vitamin C, D and E supplements were once thought to be able to prevent preeclampsia, but this proved to be untrue.  We also know that calcium, fish oil, a salt restricted diet and a high protein diet have no protective effect against preeclampsia.

  • Other Important Information
  • Women without severe preeclampsia, who are preterm, may be taken care of in the hospital or from home. If at home, you may be instructed to check your blood pressure at home every day.  Your health care provider should be called if your blood pressure is over 140/90.
  • If you have preeclampsia symptoms, notify your health care provider immediately.
  • The sooner your preeclampsia is diagnosed and you receive health care, the better the outcome for both you and your baby.



Preeclampsia FAQ

  • I have preeclampsia. Now what?

Listen to your health care provider.  Preeclampsia is a serious condition, with potential for devastating outcomes.  Preeclampsia can cause seizures, stroke and even death if not treated promptly and properly.  With appropriate treatment, complications of preeclampsia can often be prevented.

  • What does a preeclampsia headache feel like?

Most women report that a preeclampsia headache feels like the worst headache of their lives.  The pain of a preeclampsia headache tends to be in the back of the head.  Most typically, the headache does not get better with rest, hydration, or pain medication.  Even if your headache does not have these exact characteristics, you should notify your health care provider.

  • Can stress cause preeclampsia?

Even though we do not know what causes preeclampsia, we have no reason to believe that stress can cause preeclampsia.  As we explore the genetic and epigenetic (the way a gene expresses itself) factors involved with preeclampsia, it is possible that we will find that stress contributes to the development of preeclampsia.4

  • How do I know if I am at risk for preeclampsia?

We do know that some women are at higher risk than others for developing preeclampsia.



Risk factors include:

  • A first pregnancy
  • Having had preeclampsia during a previous pregnancy
  • Being under age 18 or over age 40
  • Having high blood pressure before pregnancy, or developing gestational hypertension during pregnancy
  • Obesity
  • Having diabetes, immunological disorders, kidney disease or heart disease
  • Having had a mother or sister who had preeclampsia during pregnancy
  • A pregnancy with a new partner
  • A pregnancy with twins, triplets or more
  • A pregnancy conceived via in vitro fertilization
  • Being of African-American descent1,2,3,4,5
  • Can you have preeclampsia with normal blood pressure?

In rare cases, preeclampsia without high blood pressure has been documented.  This is an unusual situation.

  • Can preeclampsia cause contractions?

Preeclampsia does not cause contractions.

  • My grandmother told me to stop eating salty food during pregnancy so that I don’t get preeclampsia. Is there a diet that can help prevent preeclampsia?

There is no preeclampsia diet.  There is specific that you can eat, or avoid eating, in order to reduce your risk of preeclampsia.  For many years, it was thought that a salt-restricted diet could prevent preeclampsia.  We have since learned that restricting salt does not effect your risk of developing preeclampsia.  In general, we advise a diet that is high in a variety of fresh fruits and vegetables, whole grains and lean proteins.2

  • I had preeclampsia in my last pregnancy. Will I have preeclampsia again?

Once you have had preeclampsia, you are at increased risk of having it in future pregnancies.  Notify your health care provider as soon as possible if you, your mother, or your sister has ever had preeclampsia.  We also advise seeing your health care provider as early in pregnancy as possible.  It is a good idea to have more frequent visits so that your blood pressure can be closely monitored.

  • Isn’t there a test to tell if I will have preeclampsia?

No.  There is currently no test available that will predict whether or not a pregnancy will be complicated by preeclampsia.  There is no accurate screening test, like there is for gestational diabetes for preeclampsia.  We also have no predictive model to work from for preeclampsia.

Much of the preeclampsia research going on is looking at the development of an accurate test for preeclampsia.  We hope to see progress on this front in the near future.2

  • Are there long term consequences of preeclampsia for me?

Women who have had preeclampsia during any pregnancy are at an increased risks for heart disease, and that increased risk last for years, if not decades.  Information that there are long-term consequences of preeclampsia is new.  We are not yet sure if it is having had preeclampsia that causes the increase in heart disease risk, or that women who experience preeclampsia have an underlying condition that puts them at risk for both preeclampsia and heart disease.

Because this information is so new, we don’t have any guidelines for monitoring this risk factor.  The existing heart disease/heart attack risk calculators do not account for a history of preeclampsia.  It may be prudent to have an evaluation by a cardiologist, a baseline EKG (electrocardiogram), and regular testing for other risk factors (such as cholesterol).  Everyone should be doing all they can to reduce their risk of cardiovascular disease.  Ways to reduce risk include breastfeeding, getting regular exercise, eating a healthy diet, maintaining a normal weight, not smoking and limiting alcohol consumption.

Because the pathological mechanisms of cardiovascular disease is similar to other conditions, such as high blood pressure and diabetes, we believe that women with a history of preeclampsia in any pregnancy are also at increased risk for these conditions after pregnancy.




  1.; Accessed 26 June 2017.
  2. 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 2013; 122:1122.
  3. MacKay AP, Berg, CJ, Atrash, HK. Pregnancy-related mortality from preeclampsia and eclampsia. Obstet Gynecol 2001; 97:533.
  4. Hypertensive Disorders. In: Cunningham F, Leveno KJ, Bloom SL, Spong CY, Dashe JS, Hoffman BL, Casey BM, Sheffield JS. Cunningham F, Leveno K.J., Bloom S.L., Spong C.Y., Dashe J.S., Hoffman B.L., Casey B.M., Sheffield J.S. Eds. F. Gary Cunningham, et al.eds. Williams Obstetrics, Twenty-Fourth Edition New York, NY: McGraw-Hill; 2013. Accessed June 25, 2017.
  5. Padden, MO. HELLP syndrome: recognition and perinatal management. American Family Physician, 1999. 60(3):829-836.
  6. Fischbach, F. A manual of laboratory and diagnostic tests, Fifth Edition Philadelphia, PA: Lippincott: 1996.


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