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High blood pressure in pregnancy - pre-eclampsia - Tommy's

What is pre-eclampsia?

Pre-eclampsia is a combination of hypertension (raised blood pressure) and proteinuria in pregnancy (the presence of protein in your urine).

The condition only occurs in pregnancy - typically after 20 weeks - and affects 2-8 percent of pregnancies.

What are the signs 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).

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
  • Heartburn that doesn’t go away with antacids
  • Rapidly increasing swelling of the face, hands or feet
  • Feeling very unwell.

What are the risks of pre-eclampsia?

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 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.

What’s the treatment for pre-eclampsia?

Mild pre-eclampsia

Before birth

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 daily dose of aspirin from the 12th week of their pregnancy until the baby is born.

Giving birth

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.

When exactly you deliver your baby will depend on how high your blood pressure is. Some hospitals may look to induce from 34-37 weeks.

Severe pre-eclampsia

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.

Before birth

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.
  • 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.

Giving birth

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.

Most women with severe pre-eclampsia will need to be delivered within two weeks of being diagnosed of it.

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 percent 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.

What causes pre-eclampsia?

The exact cause of pre-eclampsia remains unknown. Research indicates that genetics and the placenta could be factors in the development of the condition.


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.

The placenta

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, you are considered at greater risk if:

  • This is your first pregnancy/your first pregnancy with a new partner
  • You’re aged 40 or over
  • You, your mother or sister have 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 more susceptible to pre-eclampsia.

Can you suffer from pre-eclampsia after birth?

Pre-eclampsia will improve soon after your baby is born. However, you and your baby will need close monitoring 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.

Find out more about having a premature baby.

What is HELLP Syndrome?

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
  • Headache
  • 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 percent of all pregnancies, and 8-24 percent of cases with severe pre-eclampsia. The only way to treat the condition is to deliver the baby as soon as possible.

Call our midwivesIf you need more help call our midwives on
0800 0147 800

Find out more about...

Problems in pregnancy

Antenatal care in pregnancy

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Reviewed April 2014, next review April 2017


Royal College of Obstetricians and Gynaecologists, Pre-eclampsia: what you need to know, London RCGO, 2013 ( (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 ( (accessed 22 April 2015)

Macdonald S, Magill-Cuerden J, Mayes midwifery, 14th edition, London Balliere Tindall, 2011


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