Pre-eclampsia Dr Trisha Macnair Each year in the UK, around ten women and 1,000 babies die as a result of pre-eclampsia. In its mildest form it affects one in ten pregnancies, while one in 50 pregnancies are affected severely.

In this article

What's the cause? Who's affected?

What are the symptoms? What are the complications?

What's the treatment?

Although pre-eclampsia has been known about for more than 150 years, the exact cause is still not know. This means it's difficult to know who'll be affected or how to prevent it.

Although it's hard to predict which women will develop pre-eclampsia, they're at greater risk if:

• They've had it before
• Their mother or sister(s) have had it
• It's a first pregnancy, or first by a new partner
• They're over 35
• They're expecting more than one baby
• They have a chronic illness, including high blood pressure, diabetes, kidney problems and migraine

There are no symptoms in the early stages of the disease. At this point it can only be detected by checking blood pressure (which may be raised) and testing the urine for protein (known as proteinuria). These checks are a routine part of all antenatal appointments, and it's important all pregnant women attend these.

Another early sign of pre-eclampsia is swelling of the ankles, or oedema. The hands and face may swell too. Pregnant women should report any swelling, although it's common in pregnancy and may be due to less worrying causes.

Pregnant women should be aware of the early signs of pre-eclampsia because the condition can rapidly become life-threatening.

Symptoms of more serious problems may develop as pre-eclampsia progresses. These include:

• Headaches
• Blurred or altered vision
• Abdominal or shoulder pain
• Nausea and vomiting
• Confusion
• Shortness of breath

If you're worried about any symptoms, see your midwife or doctor as soon as possible.

The main risk is that pre-eclampsia will progress to one of several potentially deadly complications.

These include eclampsia, where the main problem is convulsions, which may occur before the typical high blood pressure and oedema of pre-eclampsia have developed, or after the baby has been born.

Other complications include kidney failure and HELLP syndrome, which affects as many as one in 150 advanced pregnancies.

In HELLP there's disruption of the liver, a breakdown of red blood cells and a low blood platelet count.

Pre-eclampsia accounts for about 15 per cent of premature births. The babies are not only premature but also often 'small for dates' because of growth problems.

Until recently, there was little that could be done to treat pre-eclampsia other than stop the pregnancy by delivering the baby early, usually by caesarean section.

Now treatment aims to lower blood pressure and includes strict bed rest and drugs. However, this doesn't cure pre-eclampsia - it merely holds it in check.

An injection of magnesium sulphate (the same chemical as in Epsom salts) can halve the risk of pre-eclampsia progressing to eclampsia.

Pre-eclampsia is known to involve a problem with the blood vessels in the placenta. For this reason, researchers are trying to establish whether anti-platelet drugs (such as aspirin, which make platelets in the blood less sticky) or calcium supplements may reduce the risk of pre-eclampsia.

This article was last medically reviewed by Dr Trisha Macnair in July 2006.