Pre-eclampsia is a condition that affects some pregnant women, usually during the second half of pregnancy (from around 20 weeks) or soon after their baby is delivered. Most cases occur after 24-26 weeks and usually towards the end of pregnancy.
Although less common, the condition can also develop for the first time during the first six weeks after the birth.
Most people only experience mild symptoms, but it's important to manage the condition, in case severe symptoms or complications develop. Generally, the earlier pre-eclampsia, develops the more severe the condition will be.
Early signs and symptoms of pre-eclampsia
Initially, pre-eclampsia causes:
- High blood pressure (hypertension)
- Protein in urine (proteinuria)
High blood pressure affects 10-15% of all pregnant women, so this alone doesn't suggest pre-eclampsia. However, if protein in the urine is found at the same time as high blood pressure, it's a good indicator of the condition.
As pre-eclampsia progresses, it may cause:
- Severe headaches
- Vision problems, such as blurring or seeing flashing lights
- Severe heartburn
- Pain just below the ribs
- Nausea or vomiting
- Excessive weight gain caused by fluid retention
- Feeling very unwell
- Sudden increase in oedema - swelling of the feet, ankles, face and hands
Who is affected by pre-eclampsia?
Mild pre-eclampsia affects up to 6% of pregnancies, and severe cases develop in about 1-2% of pregnancies. There are a number of things that can increase your
chances of developing pre-eclampsia, such as:
- Having diabetes, high blood pressure or kidney disease before starting pregnancy
- Having another condition, such as lupus or antiphospholipid syndrome
- Having developed the condition during a previous pregnancy
Other things that can slightly increase your chances of developing pre-eclampsia include:
- Having a family history of the condition
- Being over 40 years old
- It having been at least 10 years since your last pregnancy
- Expecting multiple babies (twins or triplets)
- Having a body mass index (BMI) of 35 or over
What causes pre-eclampsia?
Although the exact
cause of pre-eclampsia isn't known, it's thought to occur when there's a problem with the
placenta (the organ that links the baby's blood supply to the mother's).
Diagnosis of pre-eclampsia
Previously, preeclampsia was only diagnosed if a pregnant woman had high blood pressure and protein in her urine. However, experts now know that it's possible to have preeclampsia, yet never have protein in the urine. However, a single high blood pressure reading doesn't mean you have preeclampsia. If you have one reading in the abnormal range - or a reading that's substantially higher than your usual blood pressure - your doctor will closely observe your numbers. If your doctor suspects preeclampsia, you may need certain tests, including:
- Blood tests: These can determine how well your liver and kidneys are functioning and whether your blood has a normal number of platelets - the cells that help blood clot.
- Urine analysis: A single urine sample that measures the ratio of protein to creatinine - a chemical that's always present in the urine - may be used to make the diagnosis. Urine samples taken over 24 hours can quantify how much protein is being lost in the urine, an indication of the severity of preeclampsia.
- Foetal ultrasound: Your doctor may also recommend close monitoring of your baby's growth, typically through ultrasound. The images of your baby created during the ultrasound exam allow your doctor to estimate foetal weight and the amount of fluid in the uterus (amniotic fluid).
- Non-stress test or biophysical profile: A non-stress test is a simple procedure that checks how your baby's heart rate reacts when your baby moves. A biophysical profile combines an ultrasound with a non-stress test to provide more information about your baby's breathing, tone, movement and the volume of amniotic fluid in your uterus.
Treatment of pre-eclampsia
The only way to
cure pre-eclampsia is to deliver the baby, so you'll usually be monitored regularly until it's possible for your baby to be delivered. This will normally be at around 37-38 weeks of pregnancy, but it may be earlier in more severe cases.
At this point, labour may be started artificially (induced) or you may have a caesarean section.
Medication may be recommended to lower your blood pressure while you wait for your baby to be delivered.