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Written by Ada’s Medical Knowledge Team

Updated on

Pregnant woman measuring her blood pressure

What is preeclampsia?

Preeclampsia, also spelled pre-eclampsia and formerly sometimes called toxemia, is a potentially serious condition that affects only pregnant women after the 20th week of pregnancy or shortly after delivery. 1

Its characteristic symptoms are sudden-onset proteinuria (protein in the urine) and hypertension (high blood pressure). It is not yet known for certain what causes preeclampsia, but it may have something to do with abnormalities of the placental blood supply. Preeclampsia may also occur alongside HELLP syndrome, which is very serious and may progress to eclampsia, which is also very serious and may be fatal.

Preeclampsia affects only between about two and eight of every 100 pregnant women. 2 Severe preeclampsia affects only about one in every 200 pregnancies. HELLP Syndrome has a similar incidence, but around half of women with severe preeclampsia will develop HELLP Syndrome. Rates of eclampsia are low in most developed countries, with an incidence of around one in every 2000 pregnancies. However, the rate is considerably higher in developing countries. 3

Signs and symptoms of preeclampsia

Preeclampsia is often diagnosed during a routine visit to the doctor. The early signs of preeclampsia include: 1 4

  • Hypertension (high blood pressure). A blood pressure of 140 over 90 is considered a sign in women who do not have pre-existing hypertension.
  • Proteinuria (protein in the urine). This is defined as 300mg or more of protein passed in the urine over 24 hours.

Foamy urine is a sign of proteinuria. If a pregnant woman finds that her urine is foamy, she should consult a physician as soon as possible. Other symptoms which may appear as the disorder worsens include: 1 2 4 5 6

  • Headache that cannot be alleviated with painkillers
  • Edema (swelling) of hands, arms, face and/or feet
  • Blurred vision or blind spots
  • Confusion or disorientation
  • Nausea and vomiting
  • Pain in the upper right abdomen, just below the ribs or behind the breastbone
  • A pain feeling like heartburn that cannot be alleviated by antacids
  • Feeling of great unwellness
  • Oliguria (low urine output) of 500ml or less over 24 hours
  • Being unable to feel the baby move as much as previously
  • Shortness of breath, possibly due to pulmonary edema (excess fluid in the lungs)
  • Stroke. This is very rare

Good to know: If a pregnant woman suddenly discovers that their watch, bracelets or rings no longer fit their arm or hand, or that their sleeves are suddenly tight, they should seek medical help immediately.

Good to knowA sensation that feels like heartburn is also quite a common symptom among pregnant women who do not have preeclampsia. The feeling of heartburn resulting from preeclampsia can be distinguished from real heartburn by its resistance to antacid treatment.

Good to know: It should be noted that not all painkillers are safe for use in pregnancy. Pregnant women should consult with their doctor about what pain-relieving measures might work for them. If a pregnant woman has a headache that does not resolve on its own within a reasonable time, they should contact their care provider.

If any of these symptoms appear, the affected person should receive medical help as soon as possible. Without treatment, preeclampsia may become eclampsia, which is very serious and may be in rarer cases even be fatal. This is very rarely the case in developed countries, however, and adequate prenatal care may make it even less likely. 7

Hypertension and proteinuria in preeclampsia

Many women have hypertension during pregnancy, without having preeclampsia. Hypertension that results from preeclampsia is normally distinguishable from pre-existing or chronic hypertension by its sudden onset. 4 Hypertension during pregnancy is also believed to be influenced by low magnesium intake, as well as other factors, and low calcium intake leading to low levels of calcium in the body. 8 Diets with a high-calorie intake may also play a role.

It is possible for preeclampsia-related hypertension to happen at the same time as chronic hypertension. It may be quite difficult to diagnose preeclampsia in women with chronic hypertension. 9

It may be hard to diagnose preeclampsia-related proteinuria accurately in women with pre-existing proteinuria or renal diseases. One indication that preeclampsia-related proteinuria is present may be a sudden upward spike in the levels of protein being excreted.

In all of these cases, if proteinuria is present, preeclampsia is also likely to be present.

Preeclampsia headache: what does a preeclampsia headache feel like?

The headache that accompanies preeclampsia is often described as dull and throbbing and has also been described as migraine-like. 10 Importantly, it does not respond to commonly used over-the-counter painkillers.11

Good to know: It is believed that there is a link between headaches in general and migraine headaches in particular and the risk of experiencing preeclampsia. Some studies have found that women with a pre-pregnancy history of migraine headaches may have a higher risk of developing preeclampsia.

Blurred vision and visual disturbances in preeclampsia

About a quarter of women with severe preeclampsia and up to half of all women with eclampsia (see below) report visual problems, especially blurred vision. 12 Preeclampsia can cause eye problems such as: ref13 13

  • Hypertensive retinopathy, caused by high blood pressure damaging the retina or the eye
  • Exudative retinal detachment, caused by inflammation causing fluid to build up under the retina
  • Cortical blindness, caused by problems with the brain’s occipital cortex, which controls vision

Types of visual disturbances caused by preeclampsia include: 12 13

  • Blurred vision
  • Flashes of light
  • Difficulty focusing or sudden/rapidly-developing inability to focus
  • Blind spots
  • Double vision
  • Loss of vision in one or both eyes

Good to know: Visual symptoms resulting from preeclampsia are usually not permanent but transitory. Permanent vision problems as a result of preeclampsia are rare.

Abdominal pain in preeclampsia

Abdominal pain is a common symptom of preeclampsia. It is classically felt in the upper-right abdomen, below the ribs – roughly where the liver is located, but can often also be felt below the breastbone, a region known as the epigastrium, and may at times also radiate towards the right hand side of the back. 14

There is some evidence that severe upper-right abdominal pain in pregnant women indicates that the the liver has been affected, 15 which increases the risk of HELLP Syndrome developing. 16 Severe upper-right abdominal pain is an important sign that HELLP Syndrome may be developing. If a pregnant person develops upper-right abdominal pain, they should contact their physicians as soon as possible.

Signs and symptoms of severe preeclampsia

Most women with preeclampsia will not go on to develop severe preeclampsia if they are promptly treated. Signs and symptoms which can indicate severe preeclampsia include: 4

  • Worsening physical symptoms, as listed above
  • Renal insufficiency due to kidney damage from high blood pressure
  • Moderate to severe thrombocytopenia, i.e. low platelet count of 100 000 or lower
  • Twice the normal serum levels of aspartate transaminase (AST) or alanine aminotransferase (ALT) (enzymes found in the liver)

In mothers with severe preeclampsia, the unborn baby usually suffers from reduced oxygen and nutrient supply, which can retard fetal growth. Babies can be measured by medical practitioners to determine whether they are small for gestational age.

Causes of preeclampsia and subsequent eclampsia

The cause of preeclampsia is not yet completely understood by doctors. It appears to involve inflammation of maternal blood vessels, particularly those in the kidneys. This may be due to abnormalities in the way that the placental blood supply develops, which can impact the effectiveness of the attachment of the placenta to the uterine wall. 3 An imperfect attachment may cause inflammatory substances to be released into the mother’s bloodstream. It is not yet known whether preeclampsia is caused by these abnormalities or whether these abnormalities and preeclampsia share a cause.

There is some evidence that preeclampsia and heart disease share some risk factors, namely: 17

  • Endothelial dysfunction (dysfunction of the lining of the blood vessels and lymph glands)
  • Obesity
  • Hypertension
  • Hyperglycemia
  • Insulin resistance
  • Dyslipidemia (high levels of lipids in the blood).

There also appears to be a genetic component that determines a person’s risk of developing preeclampsia. If a pregnant person’s mother and/or sisters have a history of preeclampsia, their risk of preeclampsia is higher than that of a person without such a family history. Having had a previous pregnancy with preeclampsia also increases risk. 18 In such high-risk pregnancies, there is some evidence that a daily low dose (81mg/day) of aspirin may have a protective effect. 19

While the cause is uncertain, the risk factors for preeclampsia are well-known. Risk of preeclampsia is higher in women who: 1 2 4

  • Have diabetes (type 1, type 2 or gestational diabetes)
  • Are pregnant for the first time
  • Are pregnant for the first time in 10 years
  • Are having a multiple pregnancy of twins, triplets, etc.
  • Have a BMI of 35 or greater, or body weight of 90kg or greater
  • Are older than 40 or younger than 17 years old
  • Have existing high blood pressure
  • Have existing kidney disease
  • Have existing vascular disorders
  • Have existing clotting disorders
  • Have a history of preeclampsia
  • Have a family history of preeclampsia

Preeclampsia and diet

Preeclampsia is slightly more common among pregnant women from poorer communities, which may suggest that there is a connection between nutrition and preeclampsia. However, this theory has not been properly tested. A related theory is that overnutrition, especially obesity before and during pregnancy, as well as undernutrition, can both cause the risk of preeclampsia to rise. It has been suggested that low-protein diets, low-fat diets and low-energy diets may affect preeclampsia. Again, however, these hypotheses have not been proven. 20

There is some evidence that preeclampsia and atherosclerosis share risk factors, including: 20

  • Obesity
  • Insulin resistance, a condition associated with type 2 diabetes, where the body does not respond to the hormone insulin, leading to high blood glucose levels
  • Thrombophilia, a condition causing blood clots to form
  • Hyperhomocysteinemia, abnormally high levels of the amino acid homocysteine in the blood
  • African heritage

The link appears to be that both conditions increase the number of oxidants in the body. Some studies have therefore suggested that antioxidants such as Vitamin C, also known as ascorbic acid, or a Vitamin E-related compound such as tocopherol may be helpful in reducing the risk of preeclampsia.

However, trials to test the efficacy of supplementing the diet of pregnant women with antioxidants like vitamin E and vitamin C to help reduce the risk of preeclampsia have been inconclusive. 21 It is also possible that taking antioxidants as supplements might have a different effect to absorbing antioxidants through food. This theory is yet to be fully proven. 20

Diets for preeclampsia

The only things that are proven to have a positive effect on reducing the risk of preeclampsia are calcium supplements and low-dose aspirin.. A diet high in fruit and vegetables is also known to have a beneficial effect on overall health among pregnant women, therefore reducing the risk of conditions that increase the risk of preeclampsia. Lifestyle changes such as quitting smoking and cutting out alcohol can also help.

It is important to note that calcium supplementation to prevent preeclampsia is only effective in women who have low calcium intake in their diets: it does not make a difference if the pregnant person’s diet already had adequate calcium. 20 If a pregnant person is concerned that they may have low calcium, they can ask their doctor to run a test.

Omega-3 supplementation may have a protective effect against preeclampsia, but this is not known for sure. It was also formerly thought that sodium (salt) intake should be restricted to prevent preeclampsia, and, while a low-salt diet will reduce the risk of hypertension, it should not be done if it affects adequate intake of protein, calcium and energy. 20

Good to know: It is not safe for a pregnant person to begin to take unprescribed supplements or to make any significant modifications to their diets without consulting with their pregnancy care team first.

Good to know: Nobody is as yet certain whether diet can increase someone’s risk of developing preeclampsia or whether there is a way to reduce the risk of preeclampsia significantly by following a particular diet. A diet however that may lead to substantial weight gain or obesity may increase risk and should therefore not be followed.

Pregnant women should not modify their diets or begin dietary supplementation without consulting their OB-GYN team or primary physician.

Complications of preeclampsia

Most cases of preeclampsia are relatively mild and can be treated without much danger to the mother or the unborn baby. However, in some cases the situation can become more severe. HELLP Syndrome and eclampsia are two serious complications of eclampsia.

HELLP syndrome

HELLP syndrome may be considered a very severe form of preeclampsia, or a separate but overlapping disorder. The acronym HELLP stands for “hemolysis, elevated liver enzymes, low platelet count”, which refers to the main features of the condition. 2 HELLP tends to have sudden onset with similar symptoms to preeclampsia.

Good to know: HELLP Syndrome is very rare, affecting only between 4% and 12% of all women with preeclampsia. 22

Signs and symptoms that may be immediately apparent include: 2 3

  • Nausea and vomiting
  • Pain in the upper abdominal (stomach) region
  • Headache
  • Vision problems
  • Bruising easily or purple spots on the skin
  • Tender or swollen liver
  • High blood pressure

If you are concerned that you or a loved one may have HELLP Syndrome or preeclampsia, you can start a free Ada symptom assessment now.

Signs that can be determined only by testing include: 2

  • Proteinuria
  • Hemolysis (disintegrating blood cells)
  • Raised enzyme levels
  • Thrombocytopenia (low blood platelet count)

HELLP Syndrome can occur at any point after 20 weeks of pregnancy, but is most common between 27 and 37 weeks. However, between 15 % to 30 % of cases of HELLP Syndrome occur only after delivery. Long-term complications can include: 3

  • Retarded fetal growth
  • Placental abruption, i.e. separation of placenta from uterine wall before labor
  • Blood clotting problems
  • Eclampsia, i.e. seizures in pregnant women with high blood pressure
  • Liver failure

Placental abruption can reduce the supply of oxygen and nutrients to the unborn baby, increasing the risk of retarded fetal growth. In severe cases, the unborn child may not survive. 23


Eclampsia is a very serious complication of pregnancy and must be treated rapidly. 24 Despite advances in medical care, eclampsia is still a leading cause of maternal mortality. 25

Eclampsia is diagnosed when a pregnant person with preeclampsia begins to have seizures. 26. In most cases, the person with eclampsia will have shown symptoms of severe preeclampsia, but in some cases no prior symptoms of preeclampsia appear. If eclampsia is not treated rapidly, it can lead to maternal coma, brain damage, and death. 27 Worried about these or other symptoms? Get your personal Ada health assessment now.

Treatment and care

Deciding which treatment option for preeclampsia is best involves balancing the severity of the preeclampsia with the risks facing the baby. The only total cure for preeclampsia is to deliver the baby and placenta. If it is safe to do so for both the mother and the baby, the pregnancy will be maintained until the natural end of gestation, around 37 weeks.

Only if the life of the mother or the baby is in danger will labor be induced early. However, if the baby is still too young to survive outside the womb, the medical care team will take steps to maintain the pregnancy until it is safe to deliver, if it is safe for the mother to do so.

In cases of mild preeclampsia, a short period of initial hospitalization may be followed by home care as an outpatient, often extending until the baby is delivered. Home care includes: 4

  • Bed rest
  • Regular blood pressure tests
  • Regular fetal nonstress tests (NSTs) to check on the baby’s health
  • Visits to a physician two or three times a week

It can also be helpful to increase the amount of protein eaten, minimize salt intake and ensure that enough water is consumed to stay well-hydrated. 28

Hospitalization for preeclampsia

When home care is not advisable due to the severity of the symptoms, women with preeclampsia will usually be hospitalized. The treatment concentrates on managing hypertension and monitoring for complications. Treatment includes: 2 29 9

  • Medication to lower blood pressure, such as hydralazine, labetalol and nifedipine
  • Blood pressure tests at intervals of four hours, or, in severe cases, every 15 to 30 minutes
  • Urine tests for protein
  • Monitoring of hydration
  • Blood tests to monitor platelet count, clotting factors, and kidney and liver function

If preeclampsia occurs in late pregnancy, labor may be induced if the baby or the mother have blood pressure levels that cannot be controlled until the baby comes to full term. In such cases, the baby may be delivered, vaginally or by cesarean section.

In cases where the baby is only a few weeks premature, the risks to the baby’s health are low. However, if the baby is less than 34 weeks along, it is the severity of the mother’s preeclampsia that will determine whether the medical team opts to deliver the baby. 2 Outcomes for the baby may improve if the pregnancy is maintained, but treatment should not be at the expense of maternal wellbeing.

In some cases, corticosteroids may be administered to boost the baby’s lung development in order to allow it to be safely delivered earlier. 27 If corticosteroid treatment is undertaken, the baby’s heart rate should be monitored very closely. 30 If they are not thriving in the womb and have a better chance of survival if delivered, labor should be induced.

If HELLP syndrome is present, delivery will be induced regardless. 29

In cases of eclampsia, also, delivery should not be postponed unless the mother is in an unstable condition, in which case the mother should be stabilized before delivery is attempted. This should be done regardless of whether or not the baby is distressed. 9

In cases of eclampsia, the mother’s oxygen intake and seizures should be brought under control before delivery. Both baby and mother will need to be in a high-dependency unit for at least 24 hours after birth. 9 Seizures can be prevented with an intravenous dose of magnesium sulfate, and may be broken using lorazepam or diazepam. 31 Magnesium sulfate can have serious side effects and should only be administered by a skilled practitioner.

Postpartum preeclampsia

Most instances of preeclampsia happen before the baby is born, and subside soon after delivery. However, in a minority of cases, preeclampsia occurs only after delivery. If this happens, the affected person will be placed in a hospital high-dependency unit and monitored for signs of eclampsia. Once the medical team has established that they are not at risk of eclampsia, they will remain in hospital to be monitored for hypertension and further complications. 2

Good to know: In cases of postpartum preeclampsia, the baby is likely to be unaffected.


Q:What are the long-term complications for women who have had preeclampsia?
A: There is some evidence that women who had preeclampsia, eclampsia or HELLP syndrome may be at increased risk of hypertension and heart disease in later life. 9 It may also increase the risk of stroke.

Q: Will my preeclampsia have long-term effects on my child once they are born?
A: Children born to mothers with preeclampsia may be at increased risk of endocrine and nutritional diseases, 32 which can affect height and weight gain. 33

Q: Does low-dose aspirin help prevent preeclampsia?
A: There is some evidence that aspirin in low doses can have a protective effect against preeclampsia in women who are at high risk of the condition, especially those who have had preeclampsia in a previous pregnancy. The dosage range is between 75mg and 150mg a day. It’s not clear whether it’s safe to take higher doses during pregnancy. Do not begin taking aspirin without consulting a doctor.