Articles

Key takeaways

• Pre-eclampsia is a pregnancy condition affecting blood pressure and the placenta.
• Screening for pre-eclampsia happens at your booking appointment.
• Low-dose aspirin can help prevent pre-eclampsia for those at higher risk.
• Home blood pressure monitoring is safe with support from your maternity team.

What is pre-eclampsia?

Pre-eclampsia is a condition that only happens during pregnancy. It usually appears after 20 weeks of pregnancy, but can also occur up to six weeks after birth. It affects the placenta, which links your blood supply to your baby's.

The exact cause is not fully understood, but it is thought to be related to the placenta not developing properly. Pre-eclampsia causes your blood pressure to go up and usually leads to protein in your urine (proteinuria). Sometimes pre-eclampsia can affect your liver, kidneys and blood clotting without causing proteinuria. It affects around 6 in 100 pregnant women.

How pre-eclampsia can affect you and your baby

If not managed, pre-eclampsia can affect your blood vessels and damage important organs. This includes your liver, kidneys, and how your blood clots. It can also affect how well your baby's placenta works.

If your baby does not get enough blood through the placenta, their growth can be affected.

You may be advised that your baby needs to be delivered earlier than full term. While pre-eclampsia is often mild, in rare, severe cases it can become very serious for both you and your baby. This is why your maternity team will monitor you so closely.

About one in 200 women develop severe pre-eclampsia. In rare cases, severe pre-eclampsia can lead to fits, which are a type of seizure (eclampsia).

This affects about one in 4,000 pregnancies in the UK. Another serious complication is a combined liver and blood clotting disorder (HELLP syndrome).

Signs and symptoms to watch for

Pre-eclampsia may not have any symptoms at first. This is why midwives regularly check your blood pressure and test your urine for protein. If symptoms do develop, they usually happen towards the end of your pregnancy or after birth.

Symptoms of pre-eclampsia can include:

• A severe headache that does not go away with painkillers.
• Problems with your eyesight, such as blurred vision or flashing lights.
• Severe pain just below your ribs.
• Heartburn that does not go away with antacids.
• Rapidly increasing fluid retention around your face, hands, or feet.
• Feeling sick (nausea) and being sick (vomiting).
• Feeling very unwell.

If you have any of these symptoms, you should seek medical help immediately. Talk to your midwife or phone the hospital straight away.

Screening for pre-eclampsia

Screening helps identify pregnant women who may be at a higher risk of developing pre-eclampsia. There are different approaches to screening in the UK.

The National Institute for Health and Care Excellence (NICE) recommends that all pregnant women have their risk assessed. This assessment usually happens at your booking appointment, around 8 to 12 weeks of pregnancy. It involves looking at a combination of your personal risk factors.

The Fetal Medicine Foundation (FMF) offers a more comprehensive screening test. This is typically done between 11 and 13 weeks of pregnancy.

This test combines your maternal risk factors with other measurements. These include a blood test and a special ultrasound scan that checks blood flow to your womb.

The blood test measures the levels of certain proteins made by your placenta (PAPP-A and PlGF).

Limitations of screening

Both the NICE guidelines and FMF screening methods are effective at identifying women at higher risk. However, no screening test can detect all cases of pre-eclampsia.

Some women who screen negative may still develop the condition. Conversely, some women who screen positive may never develop pre-eclampsia.

Using low-dose aspirin for prevention

Low-dose aspirin can help reduce your chance of developing pre-eclampsia if you have risk factors. It is recommended by your midwife, GP, or specialist.

Who is advised to take aspirin?

You may be advised to take low-dose aspirin if you have certain risk factors. These include having high blood pressure before pregnancy or in a previous pregnancy.

You may also be advised to take it if you have a medical problem. This includes kidney issues, diabetes, or an immune system condition like lupus.

You may also be at risk if more than one of the following applies to you:

• This is your first pregnancy.
• You are aged 40 or over.
• Your last pregnancy was more than 10 years ago.
• You are overweight, with a body mass index (BMI) of 35 or more.
• Your mother or sister had pre-eclampsia during her pregnancy.
• You are carrying more than one baby, such as twins or triplets.

How to take aspirin

The typical dosage for prevention is 75 to 150 milligrams (mg) once a day. You would usually take it from 12 weeks of pregnancy until 36 weeks.

If you have more than one risk factor, you may be advised to take it until your baby is born. Always follow the guidance from your midwife or doctor.

Monitoring your blood pressure at home

Monitoring your blood pressure at home is safe when it is part of continuous assessment with your maternity care team. This is true even for women with a higher chance of developing pre-eclampsia. Your team will help you decide if home monitoring is right for you.

Your maternity care team will provide you with equipment to use at home. They will explain why monitoring is important for you and your baby.

They will also show you how to do the tests and explain what your results might show. They will tell you the levels that are safe for you.

How to measure your blood pressure

To measure your blood pressure correctly, follow these steps:

1. Preparation – Wear loose clothing with sleeves that roll up easily. You can also take your arm out of your clothing.
2. Position – Sit on a chair with your back supported and both feet flat on the floor.
3. Rest – Rest for five minutes before taking any readings.
4. Cuff placement – Slip the cuff onto your arm, usually the left arm. Position the cuff so the air tube points towards your wrist and the marker line is over the inside of your elbow.
5. Cuff adjustment – Adjust the bottom edge of the cuff so it is about two centimetres above your elbow joint. Tighten the cuff around your arm using the Velcro.
6. Arm position – Rest your arm on a table or across your lap, with your hand slightly open and palm facing upward.
7. Take reading – Press the start button on the machine. Relax and do not talk or move your arm muscles until the measurement is complete.
8. Repeat – Measure your blood pressure twice, with at least one minute between measurements.

Recording your results

Each time you measure your blood pressure, you need to record two readings. You will see two numbers. The first or top number is the pressure when your heart beats (systolic pressure, or SYS).

The second or bottom number is the pressure when your heart rests between beats (diastolic pressure, or DIA). You should record both numbers in your blood pressure monitoring diary or electronic system.

Some monitors also show a third number for your pulse (PUL or HR). You do not need to record this number.

What to do with your results

Your maternity care team will show you how to read and record your results. They will tell you which reporting systems are used in your area. Record your results in the way you have agreed with your team.

Only report your results at the agreed times. If you are ever worried about a result you have had at home, you can phone your maternity care team at any time. If you feel very unwell, contact your maternity care team immediately. This includes symptoms such as a severe headache, severe pain just below your ribs, or changes to your vision.

Your maternity care team will review your home results during your appointments. They will advise if you need any medication or further tests. If you already take medication, they will advise if changes are needed.