Reviewed April 2014, next review April 2017
Pre-eclampsia, meaning ‘before eclampsia’ is common and affects 2-8 percent of pregnancies. In most of these cases it will be a mild case and may have no effect on the pregnancy. However, if left untreated, pre-eclampsia can be very dangerous for both the mother and baby.
Pre-eclampsia only occurs during pregnancy, typically after 20 weeks. It is a combination of hypertension (raised blood pressure) and proteinuria (the presence of protein in your urine). Sometimes other organs, such as the liver or kidneys, can become affected, and there can be problems with blood clotting.
Pre-eclampsia can potentially progress to a more dangerous condition known as eclampsia, which occurs in 1-2 percent of pregnancies. Eclampsia can cause fits or convulsions. In severe cases, eclampsia can sometimes cause the death of the mother or the baby. Therefore, it is important to manage the condition safely.
Signs and symptoms of pre-eclampsia
Women with mild pre-eclampsia may not show any symptoms, and it is usually only discovered during routine antenatal appointments (through standard blood pressure checks and urine samples). The main signs are raised blood pressure combined with the presence of protein in the urine.
If pre-eclampsia gets more severe, more serious symptoms can develop, including:
- severe headache that doesn’t go away with simple painkillers
- problems with vision, such as blurring or flashing before the eyes
- severe pain just below the ribs
- heartburn that doesn’t go away with antacids
- rapidly increasing swelling of the face, hands or feet
- feeling very unwell.
Causes of pre-eclampsia
The exact cause of pre-eclampsia remains unknown. Research indicates that genetics and the placenta could be factors in the development of pre-eclampsia.
Women are more likely to suffer from pre-eclampsia if their mothers and sisters have a history of it. Women who have already had pre-eclampsia in one pregnancy have a 16 percent greater chance of developing it again in a next pregnancy.
However, women with a previous pregnancy or pregnancies without pre-eclampsia have less chance of developing it in later pregnancies. Therefore it appears that there is something in the make-up of some women that makes them more vulnerable to the condition than others.
It is believed that the placenta is involved in the development of pre-eclampsia. The placenta connects a mother to her unborn baby and the baby receives oxygen and nutrients through it. It is thought that the development of the blood vessels of the placenta is incomplete in women who develop pre-eclampsia.
Who is at risk of developing pre-eclampsia?
As we do not know the exact causes of pre-eclampsia, it is hard to predict who will develop it during pregnancy and who won’t. However, you are considered at greater risk if:
- this is your first pregnancy/your first pregnancy with a new partner,
- you are aged 40 or over,
- you, your mother or sister already had pre-eclampsia during pregnancy,
- you have a BMI (body mass index) of 35 or more/you weigh 90 kg or more,
- you are having a multiple pregnancy (twins, triplets or more),
- you have a medical problem such as high blood pressure, kidney problems and/or diabetes.
There is also some evidence that women who become pregnant from egg donation are susceptible to pre-eclampsia.
Treatment of pre-eclampsia
Pre-eclampsia can only be cured by delivering the baby so the focus of treatment is blood pressure management and monitoring the growth of the baby and the health of the mother. Women with a high risk or more than one risk factor for developing pre-eclampsia will be asked to take a daily dose of aspirin from the 12th week of their pregnancy until the baby is born.
If your regular appointments and checks pick up any symptoms of mild pre-eclampsia, you will be closely monitored for the rest of your pregnancy. You will have more frequent blood tests and scans. You may also be given medicine to control your blood pressure.
It is not recommended that you go over your due date, even with mild pre-eclampsia, so if your baby isn’t born by that date, your labour will be induced. When you deliver your baby will depend on how high your blood pressure is. Some hospitals may look to induce from 34-37 weeks. It is recommended that women with mild or moderate pre-eclampsia should give birth soon after 37 weeks.
If mild pre-eclampsia progresses to more severe pre-eclampisia you will need to be admitted to hospital in case you need treatment and/or the baby needs to be delivered. If necessary you will be given medication to control your blood pressure. You will be cared for by an experienced midwife, senior obstetrician and anaesthetist.
You may have the following tests:
- Regular blood pressure checks: If you are stable and are showing no symptoms, this will most likely be every four hours. However, if the pre-eclampsia is severe, this may be as often as every 15 minutes, and after you have stabilised, every half hour.
- Daily urine tests to measure the level of protein present.
- Blood tests: These will be taken to check your blood count, clotting, liver and kidney function.
- Ultrasound scans: These scans will help your medical team to measure your baby’s growth and wellbeing.
- Fetal heart monitoring: If pre-eclampsia is severe you may have twice weekly monitoring. While in labour, your baby’s heart rate will need to be monitored continuously.
The only way to cure pre-eclampsia completely is to deliver the baby and the placenta. This might need to be done by caesarean section, particularly if the pre-eclampsia is severe and develops early. Pre-eclampsia is therefore the cause of around 15 percent of induced premature births.
The baby is usually delivered if the doctors can’t control your blood pressure, if the liver, kidney or clotting blood tests become very abnormal, or if the baby becomes distressed.
Most women with severe pre-eclampsia will need to be delivered within two weeks of being diagnosed of it. If you develop pre-eclampsia in late pregnancy, it is common practice to induce the baby. The risk to your baby is small if he or she is born just a few weeks early.
However, if you are less than 34 weeks, the decision between delivery or other treatment will depend on the severity of the pre-eclampsia (and its risks to you and the baby) versus the risk of being born prematurely to your baby. Every situation is different and your medical team will discuss all the options with you and let you know what the risks are.
What happens after the birth?
Pre-eclampsia will improve soon after the baby is born, however you and the baby will need close monitoring in the days following the birth. The most common result of having pre-eclampsia during your pregnancy is that your baby might be small for gestational age. If you have mild pre-eclampsia it is likely that the baby will be healthy but he or she will need to be monitored closely in the days following the birth to make sure no complications develop. If your blood pressure remains high following the birth you may to take medicine for a few weeks until it returns to normal.
You will be monitored in a high dependency unit until the medical team is sure you are stable and not at risk of having eclampsia. You will need to take medicine to control your blood pressure, and you will have to rest and recover in hospital, but you are likely to make a full recovery.
Your baby’s health is also likely to be fine once he or she is born, but if he or she was born prematurely there may be complications associated with that, depending on how prematurely he or she is born.
If you have been told you are at risk of having a premature baby, you may like to read more about prematurity. You can order our comprehensive guide Having a premature baby free of charge from www.tommys.org/book
For more information on pre-eclampsia, download a copy of Tommy's pre-eclampsia leaflet.
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HELLP syndrome is a severe form of pre-eclampsia, and is potentially as dangerous as eclampsia It is most likely to occur immediately after the baby is delivered, but can appear any time after 20 weeks of pregnancy, and in rare cases before 20 weeks.
Signs include haemolysis (where the red blood cells disintegrate), raised levels of liver enzymes and a low count of platelets (which help with blood clotting).
The main symptoms are:
- nausea and vomiting,
- upper abdominal pain,
- vision problems.
It can cause severe breathing difficulties for the mother and severe health problems for the baby. HELLP syndrome occurs in 0.05 to 0.7% of all pregnancies and in 8-24% of cases with severe pre-eclampsia. The only way to treat the condition is to deliver the baby as soon as possible.
If you need more help call our midwives on
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Also in this section
Royal College of Obstetricians and Gynaecologists, Pre-eclampsia: what you need to know, London RCGO, 2013 (http://www.rcog.org.uk/womens-health/clinical-guidance/pre-eclampsia-what-you-need-know) (accessed 22 April 2015)
National Institute for Health and Care Excellence, Hypertension in pregnancy: the management of hypertensive disorders during pregnancy, clinical guideline CG107, London NICE, 2011
National Perinatal Epidemiology Unit, HELLP Syndrome, Oxford NPEU, 2011 (https://www.npeu.ox.ac.uk/ukoss/current-surveillance/hellp-syndrome#r2) (accessed 22 April 2015)
Macdonald S, Magill-Cuerden J, Mayes midwifery, 14th edition, London Balliere Tindall, 2011