What is pre-eclampsia?

Pre-eclampsia refers to persistent high blood pressure alongside protein in the urine, which usually develops after 20 weeks of pregnancy. 

For every 100 pregnant women in the UK, around one to five will develop pre-eclampsia. In most cases, pre-eclampsia is mild; however, without close monitoring and treatment when needed, it can become life-threatening to the mother and baby. 

Here, we will explore pre-eclampsia symptoms, causes, complications and treatments, as well as how you can reduce your risk of pre-eclampsia.  

What is the difference between pre-eclampsia and eclampsia?

Pre-eclampsia was originally identified as a warning sign that preceded eclampsia.

Eclampsia, also known as an eclamptic fit, refers to sudden seizures that occur as a result of pre-eclampsia. This is a rare complication of pre-eclampsia that affects around one in 4,000 pregnant women in the UK.

Symptoms of pre-eclampsia

In the early stages of pre-eclampsia, you are unlikely to notice any symptoms. However, your midwifery team will be able to pick up early signs of pre-eclampsia from the blood pressure measurements and urine tests that are part of your routine antenatal appointments. 

Two of the earliest signs of pre-eclampsia are high blood pressure and high protein levels in your urine (proteinuria).

Early symptoms that you may notice include: 

• Heartburn that is not relieved by taking antacids
• Nausea and vomiting
• Pain below your ribs (epigastric pain) on the right side caused by the effects of pre-eclampsia on your liver
• Severe, persistent headaches
• Sudden swelling of your face, hands, ankles and/or feet
• Visual changes including blurred vision, seeing flashing lights and sensitivity to light

Pre-eclampsia can develop gradually or suddenly. You should inform your midwife and/or GP as soon as you notice any of the symptoms of pre-eclampsia. 

Pre-eclampsia without high blood pressure

In the vast majority of cases, high blood pressure is a key feature of pre-eclampsia. However, there are rare cases where pregnant women develop symptoms of pre-eclampsia (eg severe headaches, blurred vision, epigastric pain, etc) without high blood pressure. 

What is the difference between pre-eclampsia and gestational hypertension?

Both pre-eclampsia and gestational hypertension refer to persistent high blood pressure after 20 weeks of pregnancy. However, with gestational hypertension, there is no protein in the urine. 

Also, gestational hypertension does not usually cause any noticeable symptoms, while pre-eclampsia causes multiple symptoms, including severe headaches, swelling of the face, hands, feet and ankles, nausea, etc. 

How does pre-eclampsia affect the baby?

Pre-eclampsia causes reduced blood supply to the placenta, which is responsible for providing nutrients and oxygen to the growing baby. 

Consequently, in women with pre-eclampsia, the baby may grow more slowly (foetal growth restriction). If pre-eclampsia occurs before 37 weeks, babies are often born with lower birth weights.

Pre-eclampsia also increases the risk of pre-term birth. In severe pre-eclampsia, a planned pre-term birth may be needed to reduce the risk of harm to the baby and/or mother. 

Depending on how early the baby is delivered, their organs may not be fully developed. This can lead to complications including breathing difficulties, such as neonatal respiratory distress syndrome, and feeding difficulties, such as feeding intolerance.  

Pre-eclampsia complications in the mother 

In the immediate future, pre-eclampsia increases the risk of placental abruption, HELLP syndrome, eclampsia and damage to other organs. 

Placental abruption 

This refers to the separation of the placenta from the inner wall of the womb before the baby is born. This can reduce the amount of nutrients and oxygen the baby receives, which can harm their development, and can cause heavy bleeding in the mother, which can be life-threatening. 

In severe cases of placental abruption, the baby may need to be delivered immediately. 

HELLP syndrome 

This refers to haemolysis, elevated liver enzymes and low platelet count syndrome. For every 25 women who have pre-eclampsia, between two and six will develop HELLP. When this occurs, too many red blood cells are broken down, the liver is damaged, causing high levels of liver enzymes, and factors that allow blood clots to form (platelets) are reduced. 

HELLP syndrome needs urgent treatment as it can lead to stroke or liver rupture, both of which are life-threatening.

Eclampsia

Eclampsia occurs in three in every 100 women with pre-eclampsia and causes potentially life-threatening seizures. Depending on the severity of the seizures, this can lead to confusion, disorientation, urinary incontinence, loss of consciousness, coma, stroke and brain damage.

Organ damage and long-term consequences

Pre-eclampsia also increases the risk of kidney failure, liver failure and a build-up of fluid around the lungs (pulmonary oedema) that impairs breathing. 

In the longer term, pre-eclampsia increases the risk of chronic (long-term) high blood pressure, as well as cardiovascular disease. These risks are higher if you have pre-eclampsia more than once. 

What causes pre-eclampsia? 

The exact cause of pre-eclampsia is unknown. However, it starts with impaired formation of the blood vessels that grow during pregnancy to supply oxygen and nutrients to the placenta. 

In mothers with pre-eclampsia, these blood vessels either do not form or do not function properly. This leads to disrupted blood flow through the placenta, which is thought to disrupt how blood pressure is regulated in the mother. 

Risk factors for pre-eclampsia

You are more likely to develop pre-eclampsia if you: 

• Are aged 35 or over
• Are pregnant for the first time or for the first time with a new partner
• Are pregnant with more than one baby
• Had complications in a previous pregnancy
• Have a family history of pre-eclampsia
• Previously had pre-eclampsia 

You are also more likely to develop pre-eclampsia if you have certain health conditions before pregnancy, including:  

• Autoimmune conditions eg systemic lupus erythematosus or antiphospholipid syndrome
• Chronic high blood pressure
• Diabetes
• Kidney disease
• Obesity

Diagnosing pre-eclampsia

Pre-eclampsia is diagnosed through regular monitoring of your blood pressure and urine tests, which are part of routine antenatal appointments.

If your doctor suspects you have pre-eclampsia based on these results and/or any symptoms you develop, they may recommend a blood test to check for levels of the protein placental growth factor. 

Low placental growth factor levels suggest pre-eclampsia but are not a definitive test for the condition. You may, therefore, need additional blood tests (eg a blood platelet count and liver enzymes test) and a foetal ultrasound scan to monitor your baby’s growth. 

Treating pre-eclampsia 

There is no medical cure for pre-eclampsia. It only resolves after giving birth. Consequently, if you are diagnosed with pre-eclampsia, you and your baby will be closely monitored. 

For the mother, this will include regular blood tests to check liver and kidney function, blood pressure measurements and urine tests to check for protein. For the baby, this will include regular foetal ultrasound scans to check their growth and may also include cardiotocography to check for signs of distress by electronically measuring the baby’s heart rate.  

Depending on the severity of your pre-eclampsia, you may need to visit the hospital daily for monitoring. 

You may also be given medication to lower your high blood pressure. If you have already had an episode of eclampsia (fitting), you will be given anticonvulsant medication. This is also prescribed if you have severe pre-eclampsia and are due to deliver your baby within 24 hours. 

Your care team will support you to carry your pregnancy for as long as possible with the aim of delivering your baby between weeks 37 and 38 when they are fully developed (full term). 

However, if you have severe pre-eclampsia and there is significant risk to you or your baby, your doctor may recommend delivery before 37 weeks ie a planned preterm birth. 

Postpartum pre-eclampsia 

Postpartum pre-eclampsia is less common than pre-eclampsia. It occurs after giving birth and can develop any time within the first six weeks after birth. However, the risk is highest during the first seven days. 

Risk factors for developing postpartum pre-eclampsia are the same as for pre-eclampsia. While you are more likely to develop postpartum pre-eclampsia if you have pre-eclampsia, not having pre-eclampsia does not rule out developing postpartum pre-eclampsia.

Postpartum pre-eclampsia is treated by taking medication to lower your blood pressure and, in severe cases, anticonvulsant medication to prevent fits. You will be closely monitored until your postpartum pre-eclampsia resolves. 

How to prevent pre-eclampsia 

Depending on your particular risk factors for developing pre-eclampsia, you can take steps to reduce your risk. For example, if you are overweight or obese, before you become pregnant, you can try to lose any excess weight. 

If you have diabetes, make sure you continue to manage your blood sugar levels throughout your pregnancy. Similarly, if you have high blood pressure, make sure you continue to manage your blood pressure during your pregnancy.

If your doctor identifies you as someone at higher risk of pre-eclampsia – this will usually be assessed at your 12-week foetal ultrasound scan appointment – they may advise you to take a low dose of aspirin every day. This is proven to reduce the risk of pre-eclampsia in those with a higher risk of developing the condition. 

In addition, regular exercise, following a healthy diet and getting a good night’s sleep each night will reduce your risk of pre-eclampsia.