What is pre-eclampsia?

Also known as pre-eclamptic toxaemia (PET) or pregnancy induced hypertension (PIH), pre-eclampsia is a potentially serious condition that can occur in the later stages of pregnancy (after 20 weeks). It affects as many as one in ten pregnant women and is severe in one in 100.

Pre-eclampsia is characterised by high blood pressure, protein in the urine and oedema (leakage of fluid into tissues causing swelling). If left unrecognised or untreated, pre-eclampsia can lead to slow foetal growth due to a reduced blood flow and oxygen supply to the baby and may eventually develop into the potentially life-threatening complication of eclampsia. This is a very serious condition that can result in stroke or death.

What causes pre-eclampsia?

Pre-eclampsia is a multisystem (affecting all organs) disorder of pregnancy and the exact cause is unclear. Some research indicates that it may arise due to problems with the immune response to pregnancy, in particular, how completely the placenta implants into the lining of the uterus. Some research also indicates that it has a genetic basis.


A number of risk factors have been identified as increasing a woman's risk of developing pre-eclampsia.

• Women who are having their first baby (primagravid);
• Women under 20 years of age or over 36 years of age;
• Women with a multiple pregnancy;
• Family history of pre-eclampsia;
• Women with pre-existing medical problems such as hypertension (high blood pressure), diabetes, kidney disease;
• Women with a history of migraine are also at increased risk of developing pre-eclampsia.

Women who have pre-eclampsia in their first pregnancy are at increased risk of having a recurrence in a subsequent pregnancy. However, the condition is likely to be less severe if present at a later gestation.


There is no way to prevent pre-eclampsia. Certain drugs and dietary supplements such as aspirin, magnesium, calcium and fish oil have been proposed as preventative measures but there is little or no evidence that these measures work. There is promising research indicating that vitamin C, and possibly vitamin E, supplements may help prevent pre-eclampsia.

What symptoms should I look out for?

Pre-eclampsia usually presents late in pregnancy, after the sixth month. It does not always have outward symptoms, especially in mild cases, and many women who are diagnosed as having the condition are surprised because they are not feeling unwell. Your doctor or midwife will be alerted to the presence of pre-eclampsia, however, if routine antenatal checks show that you have:

• Raised blood pressure (hypertension);
• Protein in your urine, which is a sign of potential damage to the kidneys;
• Swelling (oedema) of the feet ankles or hands or face;
• Sudden excessive weight gain (due to fluid retention);
• Vomiting or nausea.

If your blood pressure is very high you may experience headaches, flashing lights and blurred vision and feel generally unwell.

It is a combination of hypertension and raised levels of protein in the urine (protenuria), with or without accompanying oedema that confirms the diagnosis of pre-eclampsia. Ankle oedema, which is common during pregnancy, affecting about 80% of women, is not specific for pre-eclampsia.

How is pre-eclampsia treated?

Pre-eclampsia is cured by delivery of the baby. All signs and symptoms of the condition, including hypertension, are usually resolved within about two weeks of the baby's delivery, although some women do continue to have raised blood pressure for up to six weeks and may require anti-hypertensive medication to bring it under control.

If you are diagnosed with pre-eclampsia quite early in your pregnancy and your baby is not sufficiently developed to live outside the womb, your condition and that of your baby will be monitored closely. Depending on how severe the pre-eclampsia is, you will either be admitted to hospital or attend a special day unit until your pregnancy has progressed to a point where it is safe to deliver the baby (as near term as possible).

If you have a mild form of pre-eclampsia, rest and regular monitoring of your blood pressure may be all that is required. You may be prescribed anti-hypertensive drugs to lower your blood pressure. Blood samples may be tested on a regular basis to keep a check on your renal and liver function and your urine will be checked regularly for protein levels. The clotting factors in your blood may also be monitored regularly, particularly if your pre-eclampsia is severe enough for you to be admitted to hospital. Ultrasound scanning will be used to check your baby's growth and Doppler scanning to check his/her blood supply.

If your condition deteriorates at any time, or there is evidence that the placenta is not working properly or you are close to your expected date of delivery your obstetrician may decide to induce labour (if you are more than 36 weeks into your pregnancy) or deliver the baby by caesarean section (if you are less than 36 weeks gestation).

Will my baby be at risk?

In most cases of pre-eclampsia, there is a happy outcome for mother and baby. If your baby is premature he may need special care in the neonatal intensive care unit. Babies born to mothers with pre-eclampsia tend to be small for dates, which puts them at a higher risk of problems such as low blood glucose and they may need to spend some time in the intensive care unit to manage this


Written by Medpages Editorial Team
Last Editorial Review: 25/1/2010