Pre-eclampsia is a complication of pregnancy. Women with pre-eclampsia have high blood pressure, protein in their urine, and may develop other symptoms and problems. The more severe the pre-eclampsia, the greater the risk of serious complications to both mother and baby. Pre-eclampsia is thought to be due to a problem with the afterbirth (placenta), and so delivering the baby early is the usual treatment. Medication may be advised to help prevent complications.

What are pre-eclampsia and eclampsia?

Pre-eclampsia is a condition that only occurs during pregnancy. It causes high blood pressure, protein leaks from the kidneys into the urine, and other symptoms may develop (see below). It usually develops sometime after the 20th week of pregnancy. The severity of pre-eclampsia can vary. Serious complications may affect the mother, the baby, or both. The more severe the condition becomes, the greater the risk that complications will develop.

Eclampsia is a type of seizure (convulsion) which is a life-threatening complication of pregnancy. About 1 in 100 women with pre-eclampsia develop eclampsia. So, most women with pre-eclampsia do not progress to have eclampsia. However, a main aim of treatment and care of women with pre-eclampsia is to prevent eclampsia and other possible complications (listed below).

Who gets pre-eclampsia?

Any pregnant woman can develop pre-eclampsia. It occurs in about 1 in 14 pregnancies. However, you have an increased risk of developing pre-eclampsia if you:

• Are pregnant for the first time, or are pregnant for the first time by a new partner. About 1 in 30 women develop pre-eclampsia in their first pregnancy.
• Have had pre-eclampsia before.
• Have a family history of pre-eclampsia. Particularly if it occurred in your mother or sister.
• Had high blood pressure before the pregnancy started.
• Have diabetes, systemic lupus erythematosis (SLE), or chronic (persistent) kidney disease.
• Are aged below 20 or above 35.
• Have a pregnancy with twins, triplets, or more.
• Are obese.

What causes pre-eclampsia?

• The cause is not known. It is probably due to a problem with the placenta (the afterbirth). This is the attachment between the baby and the mother's uterus (womb). It is thought that the blood vessels in the placenta do not develop properly. This may affect the transfer of oxygen and nutrients to the baby.
• Pre-eclampsia can also affect various other parts of the mothers body. It is thought that substances released from the placenta (afterbirth) go around the body and damage the blood vessels, making them become leaky.
• Pre-eclampsia runs in some families so there may be some genetic factor.

How is pre-eclampsia detected?

Pre-eclampsia can develop anytime after 20 weeks of pregnancy. Pre-eclampsia is present if:

• your blood pressure becomes high, and
• you have an abnormal amount of protein in your urine.

Understanding blood pressure readings

Normal blood pressure is below 140/90 mmHg. The first number (systolic pressure) is the pressure at the height of the contraction of the heart. The second number (diastolic pressure) is the pressure in the arteries when the heart rests between each heart beat.

• Mildly high blood pressure is 140/90 mmHg or above, but below 160/100 mmHg.
• Moderate to severe high blood pressure is 160/100 mmHg or above.

High blood pressure can be:

• just a high systolic pressure, for example, 170/70 mmHg.
• just a high diastolic pressure, for example, 130/104 mmHg.
• or both, for example, 170/110 mmHg.

However, any substantial rise in the blood pressure from a reading taken in early pregnancy is a concern, even if it does not get as high as the levels listed above. (You may have quite low blood pressure to start with.)

Is pre-eclampsia the same as high blood pressure of pregnancy?

No. Many pregnant women develop mild high blood pressure. Most do not have pre-eclampsia. With pre-eclampsia you have high blood pressure, plus protein in your urine, and sometimes other symptoms and complications listed below. About 1 in 5 pregnant women with high blood pressure progress to pre-eclampsia.

Therefore, if you develop mild high blood pressure, it is vital that you have regular ante-natal checks which can detect pre-eclampsia, if it occurs, as early as possible.

What are the symptoms of pre-eclampsia and how does it progress?

The severity of pre-eclampsia is usually (but not always) related to the blood pressure level. You may have no symptoms at first, or if you have only mildly raised blood pressure and a small amount of leaked protein in your urine. If pre-eclampsia becomes worse, one or more of the following symptoms may develop. See a doctor or midwife if any of these occur.

• Headaches.
• Blurring of vision, or other visual problems.
• Abdominal (tummy) pain. The pain that occurs with pre-eclampsia tends to be mainly in the upper part of the abdomen, just under the ribs.
• Vomiting.
• Just not feeling right.

Swelling or puffiness of your feet, face, or hands (oedema) is also a feature of pre-eclampsia. However, this is common in normal pregnancy. Most women with this symptom do not have pre-eclampsia, but it can become worse in pre-eclampsia. Therefore, report any sudden worsening of swelling of the hands, face or feet promptly to your doctor or midwife.

Regular checks may be all that you need if pre-eclampsia remains relatively mild. If pre-eclampsia becomes worse, you are likely to be admitted to hospital. Tests may be done to check on your well-being, and that of your baby. For example, blood tests to check on the function of your liver and kidneys. Also, an ultrasound scan is usual to see how well your baby is growing.

What are the possible complications of pre-eclampsia?

Most women with pre-eclampsia do not develop serious complications. The risks increase the more severe the pre-eclampsia becomes.

For the mother
Serious complications are uncommon but include the following.

• Eclampsia (described above).
• Liver, kidney, and lung problems.
• A blood clotting disorder.
• A stroke (bleeding into the brain).
• Severe bleeding from the placenta.
• HELLP syndrome occurs in about 1 in 5 women who have severe pre-eclampsia. HELLP stands for 'haemolysis, elevated liver enzymes and low platelets' which are some of the medical features of this severe form of pre-eclampsia. Haemolysis means that the blood cells start to break down. Elevated liver enzymes means that the liver has become affected. Low platelets means that the number of platelets in the blood is low and you are at risk of serious bleeding problems.

For the baby
The poor blood supply in the placenta can reduce the amount of nutrients and oxygen to the growing baby. On average, babies of mothers with pre-eclampsia tend to be smaller. There is also an increased risk of stillbirth.

About 10 women, and several hundred babies, die each year in the UK from the complications of severe pre-eclampsia. The risk of complications is reduced if pre-eclampsia is diagnosed early and treated.

What is the treatment for pre-eclampsia?

Delivering the baby
The only complete cure is to deliver the baby. At delivery the placenta (often called the afterbirth) is delivered just after the baby. Therefore, the cause of the condition is removed. After the birth, the blood pressure and any other symptoms in the mother usually soon settle.

It is common practice to induce labour if pre-eclampsia occurs late in the pregnancy. A caesarean section can be done if necessary. The risk to the baby is small if he or she is born just a few weeks early. However, a difficult decision may have to be made if pre-eclampsia occurs earlier in the pregnancy. The best time to deliver the baby has to balance several factors which include:

• The severity of the condition in the mother, and the risk of complications occurring.
• How badly the baby is affected.
• The chance of a premature baby doing well. As a rule, the later in pregnancy the baby is born, the better. However, some babies grow very poorly if the placenta does not work well in severe pre-eclampsia. They may do much better if they are born, even if they are premature.

As a rule, if pre-eclampsia is severe, then delivery sooner rather than later is best. If the pre-eclampsia is not too severe, then postponing delivery until nearer full term may be best.

Other treatments
Until the baby is delivered, other treatments that may be considered include:

• Magnesium sulphate. Studies have shown that if mothers with pre-eclampsia are given magnesium sulphate, it roughly halves the risk of developing eclampsia. Magnesium sulphate is an anticonvulsant, but prevents eclampsia much better than other types of anticonvulsants which are used for epilepsy. It does not affect the outcome of the baby, but the risk of serious consequences to the mother are much reduced. Magnesium sulphate is used especially in women with severe pre-eclampsia where there is a greater risk of developing eclampsia. Magnesium sulphate is given for about 24-48 hrs by a 'drip' (a slow infusion directly into a vein). It is usually given around the time of delivery.
• Medication to reduce blood pressure may be an option for a while if pre-eclampsia is not too severe. If the blood pressure is reduced it may help to allow the pregnancy to progress further before delivering the baby.
• Rest is often advised, although there is little evidence that this makes much difference. However, it is common practice to admit women with pre-eclampsia to hospital, particularly if it is severe. This is not just for rest, but also to monitor the mother and developing baby.

Can pre-eclampsia be prevented?

There is some evidence to suggest that regular low dose aspirin and calcium supplements may help to prevent pre-eclampsia in some women. These are not standard or routine treatments as the evidence for their benefit is not strong or conclusive. However, one or other may be considered by a specialist if you have a particularly high risk of developing pre-eclampsia. (Do not take these unless specifically advised to do so by a specialist.)

Will pre-eclampsia develop in my next pregnancy?

• If you had pre-eclampsia in your first pregnancy, you have about a 1 in 10 chance of it recurring in future pregnancies. However, this means you have about a 9 in 10 chance of it not happening again. There is no way of predicting if you will develop it again.
• If you do not have pre-eclampsia in your first pregnancy, it is unusual to develop it in future if you become pregnant again by the same partner.

Routine care for women with pre-eclampsia or at risk of pre-eclampsia

Current guidelines recommend that when you are less than 20 weeks pregnant, you should be referred to a specialist (obstetrician) for assessment if you have any of the following (which put you at an increased risk of developing pre-eclampsia later in the pregnancy):

• Multiple pregnancy (twins, triplets, quads, etc).
• One of the following underlying medical conditions:
  • Pre-existing high blood pressure, or a blood pressure reading at the first (booking) antenatal appointment of 90 mmHg or above.
  • Pre-existing kidney disease, or protein in the urine at the first antenatal appointment.
  • Pre-existing diabetes.
  • Antiphospholipid antibodies.
• Pre-eclampsia in any previous pregnancy.
• The presence of two or more of the following:
  • It is your first pregnancy.
  • You are 40 years of more.
  • You are obese with a BMI of 35 or more.
  • You have a family history of pre-eclampsia.
  • You have a diastolic blood pressure at the first antenatal appointment between 80 and 90 mm Hg. (This is just below the cut off level of 'high' which is 90 mmHg.)

Women who develop pre-eclampsia (which usually develops sometime after 20 weeks of pregnancy) should be referred promptly to a specialist for assessment and care.

Further help and information

APEC (Action on Pre-EClampsia)
84-88 Pinner Road, Harrow, Middlesex, HA1 4HZ
Helpline: 020 8427 4217 (Weekdays 10am - 3pm)    Web: www.apec.org.uk

© EMIS and PIP 2006   Updated: June 2006   PRODIGY Validated

The authors and editors of this article are employed to create accurate and up to date content reflecting reliable research evidence, guidance and best clinical practice. They are free from any commercial conflicts of interest. Find out more about updating.

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