Pre-eclampsia is the most common of the serious complications of pregnancy. It is caused by a defect in the placenta, which joins mother and baby and supplies the baby with nutrients and oxygen from the mother's blood. Pre-eclampsia is symptom-less in the early stages and is detectable only by regular antenatal checks on the mother's blood pressure and urine.

In its widest forms, pre-eclampsia affects about one in 10 pregnancies overall and one in 50 pregnancies severely. Pre-eclampsia can be very serious and is still responsible for the deaths of between three and five women a year, as well as between 500 and 600 babies.

It is potentially life-threatening to mother and baby if allowed to develop and progress undetected.

Pre-eclampsia is curable only by delivery, which puts some babies at risk of death from prematurity. Pre-eclampsia cannot be predicted, reliably prevented or treated to allow the pregnancy to continue. Although first identified more than 150 years ago, its prime cause remains unknown.

The size of the global problem
Pre-eclampsia is a massive problem throughout the world. Every year, between 1.5 and 8 million women devlop pre-eclampsia. Of these women, approximately 150,000 have eclamptic convulsions. It is believed that, conservatively, between 40,000 and 60,000 women die each year and approximately 12% of their babies die within the first month. Globally, pre-eclampsia is associated with approximately 4,000,000 growth-restricted babies.

Your Antenatal Care
The antenatal care system in the UK was set up in order to detect the development of pre-eclampsia. Because the symptoms of pre-eclampsia cannot easily be detected by you it is important that you attend each of your antenatal appointments. At each of your appointments, you should have your blood pressure checked and your urine tested for the presence of proteinuria.

If you are felt to be at higher risk of developing pre-eclampsia then your consultant might well decide on a different pattern of care for you which may involve more routine visits.

What is blood pressure?
Blood pressure is the force of blood pumping around your body. It is measured in your upper arm with an inflatable cuff. The blood pressure is recorded as two numbers: the first (and the highest) number shows the pressure during a heartbeat; the second shows the pressure between beats. Blood pressure varies between people. It also changes with the time of day and what you are doing. An average blood pressure of 110/70 or 120/80 is normal for women. But yours may be slightly higher or lower and still be completely normal for you.

Blood pressure in pregnancy
Your midwife will find out your blood pressure at your first antenatal appointment. She or your doctor will check it again at every visit after that, and between visits if necessary. Blood pressure often falls around the middle of pregnancy, then rises back up to normal in the last few weeks. If it keeps on rising, you may be getting pre-eclampsia and will need to have extra checks.

What if my blood pressure is high?
Stress, worry or activity can raise your blood pressure for a while. But if it stays up, you may be getting pre-eclampsia. There is no clear line between normal and high blood pressure. But doctors and midwives normally worry about readings of 140/90 or more. If your blood pressure is high, your midwife or doctor will need to check it more often – maybe every few days. Each time they check it, they should also check your urine for protein and ask if you feel ill.

Why is urine checked in pregnancy?
Your urine gives vital clues to your health and that of your baby. It is checked regularly for:

- Bacteria – a sign of infection

- Glucose (sugar) – a possible sign of diabetes, which can appear for the first time in pregnancy.

- Protein – a possible sign of pre-eclampsia.

How the test works
Your midwife or doctor dips a paper strip (dipstick) into a fresh sample of urine. The test shows if protein is present and if so, how much protein there is. A tiny amount of protein is written in your notes as a 'trace'. This is nothing to worry about. More than a trace of protein is noted as one or more + signs, up to four at the most. The more + signs you have, the greater the risks for you and your baby.

What if protein is found?
If you have + or more of protein and high blood pressure, you may have pre-eclampsia and will need extra care from now on. If your blood pressure is normal, your urine may be re-checked for other problems, such as infection. If no other cause for the protein is found, your urine and blood pressure should be checked often from now on, in case you are developing pre-eclampsia.

Collecting a urine sample at home
You may be asked to collect your own urine samples at home and bring them to the clinic for checking. You may be given a special container or be asked to find one yourself. Whatever container you use, be sure to keep it clean and well rinsed. Make sure you drink enough water before you give a sample, as this will increase your chances of an accurate reading.

There are three types of sample you may be asked to collect. Here's how to do them:

First-morning specimen
On the day of your appointment, collect some of your first urine passed after waking up.

Mid-stream specimen (MSU)
Clean your genital area with water. Then use the '3S' plan as follows:

Start – pass a small amount of urine into the toilet.
Stop – while you still have plenty more to do.
Sample – start again and fill the container.

Then pass any remaining urine into the toilet. If you forget to bring your sample to the clinic, ask for a container and collect a fresh sample while you are there.

24-hour specimen
Collect all the urine you pass over a 24-hour period:

Step 1
After waking, empty your bladder into the toilet without collecting a sample. Your midwife or doctor may ask you to do this at a set time of the morning.

Step 2
Collect all the urine you pass during the rest of that day and night. Empty your sample container each time into the larger one given by the clinic.

Step 3
Exactly 24 hours after Step 1, collect your last sample and add it to the container.