What is pre-eclampsia?
Pre-eclampsia is a condition that only occurs in pregnancy - typically after 20 weeks - and affects 2-8 in 100 women. It is diagnosed through a combination of hypertension (raised blood pressure) and proteinuria in pregnancy (the presence of protein in your urine).
Up to 6% of UK pregnancies will be affected by pre-eclampsia.
Read more pre-eclampsia statistics.
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).
If the condition gets more severe, various pre-eclampsia 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
- Nausea or vomiting
- Heartburn that doesn’t go away with antacids
- Rapidly increasing swelling of the face, hands or feet (for example if your watch or rings suddenly don't fit.)
- Feeling very unwell.
These symptoms are serious and you should seek medical help immediately.
Most cases of pre-eclampsia are mild and may have no effect on the pregnancy.
However, if left untreated, pre-eclampsia can be dangerous for both the mother and baby.
Sometimes other organs, such as the liver, 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% 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.
Pre-eclampsia can only be cured completely by delivering the baby and the placenta. If your regular prenatal appointments and checks pick up any symptoms of mild pre-eclampsia the focus of treatment before birth will be blood pressure management, and monitoring the growth of the baby and the health of the mother.
You may also be given medicine to control high blood pressure in pregnancy: Women with a high risk or more than one risk factor for developing pre-eclampsia will be asked to take a low daily dose of aspirin from the 12th week of their pregnancy until the baby is born.
It’s 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. 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.
Pre-eclampsia is a risk factor for premature birth
If mild pre-eclampsia progresses to more severe pre-eclampsia, you’ll need to be admitted to hospital. That way you’re in the right place if you need treatment and/or if the baby needs to be delivered early.
If necessary you’ll be given medication to control your blood pressure. You’ll be cared for by an experienced midwife, senior obstetrician and anaesthetist.
You may have the following tests:
- Regular blood pressure checks: If you’re 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.
- You may be on a fluid balance chart to monitor your hydration.
- 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.
If you develop pre-eclampsia in late pregnancy, it is common practice to induce the baby. 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.
The risk to your baby is small if he or she is born just a few weeks early. Pre-eclampsia is the cause of around 15% of induced premature births.
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.
The exact cause of pre-eclampsia remains unknown. Research indicates that genetics and the placenta could be factors in the development of the condition. Read more about our pre-eclampsia research.
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% 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’s 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’s thought that the development of the blood vessels of the placenta is incomplete in women who develop pre-eclampsia.
Am I at risk of developing pre-eclampsia?
As we don’t know the exact causes of pre-eclampsia, it’s hard to predict who will develop it during pregnancy and who won’t. However, there are some things that tell health professionals that you are at greater risk of pre-eclampsia.
The following indicate that you are at a high risk:
- you have had pre-eclampsia in a previous pregnancy
- hypertensive disease during a previous pregnancy
- you have chronic kidney disease
- you have autoimmune disease such as systemic lupus erythematosus or antiphospholipid syndrome
- you have type 1 or type 2 diabetes
- you have chronic hypertension (high blood pressure).
You will be offered a daily dose of aspirin from 12 weeks onwards if you have ONE of the above.
The following indicate that you are at moderate risk:
- this is your first pregnancy/your first pregnancy with a new partner
- this is your first pregnancy in 10 or more years
- you’re aged 40 or over
- you are having a multiple pregnancy (twins, triplets or more)
- you, your mother or sister have already had pre-eclampsia during pregnancy
- you have a BMI (body mass index) of 35 or more
You will also be offered a daily dose of aspirin from 12 weeks if you have TWO of the above.
There is also some evidence that women who become pregnant from egg donation are more susceptible to pre-eclampsia.
Can you suffer from pre-eclampsia after birth?
Pre-eclampsia will improve soon after your baby is born. You will be closely monitored in the days following the birth.
If you have severe pre-eclampsia, 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. However, your baby will need to be monitored closely in the days following the birth to make sure no complications develop.
If he or she was born prematurely there may be some complications associated with that. The most common result of having pre-eclampsia during your pregnancy is that your baby might be small for gestational age.
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.
- haemolysis (where the red blood cells disintegrate)
- raised levels of liver enzymes
- a low count of platelets (which help with blood clotting).
The main symptoms are:
- Nausea and vomiting
- Upper abdominal pain
- Vision problems.
The only way to treat the condition is to deliver the baby as soon as possible.
Read about our hypertension research.