Pregnancy - preeclampsia

What is preeclampsia?#

Preeclampsia is a disorder of pregnancy marked by high maternal blood pressure and protein in the urine. It is the most common serious medical complication of pregnancy, affecting around 5 to 8 per cent of all pregnancies. In about 1 to 2 per cent of cases it is severe enough to threaten the lives of both the mother and her unborn baby.

The causes are not fully understood, but genetic factors and the placenta seem to play significant roles. Preeclampsia is more common in first pregnancies than in later ones. The mother’s blood pressure usually returns to normal after the baby is born and the placenta is delivered.

Preeclampsia can develop at any time during the second half of pregnancy, but most often appears in the later stages. In its mildest form, protein shows up in a urine test and blood pressure is only slightly raised. The seriousness of the condition is judged largely by the level of the blood pressure, and preeclampsia can become very serious. All forms need to be treated.

Who is at risk?#

It is difficult to predict who will be affected, but some women appear to be more at risk than others, including those in their first pregnancy and those who are pregnant with more than one baby.

Symptoms of preeclampsia#

Preeclampsia often has no obvious symptoms at first, and most women feel well. That is why regular antenatal checks of your blood pressure are so important.

Early signs can include:

• High blood pressure
• Proteinuria (protein in the urine)
• Sudden swelling of the face, hands or feet

Some swelling of the feet and ankles is a common and normal part of pregnancy, but sudden swelling of the face, hands or feet can be a sign of preeclampsia. As the condition advances, symptoms can include headache, visual disturbances, dizziness and vomiting. Because some symptoms overlap with normal pregnancy, women may dismiss the early warning signs, which is another reason regular antenatal blood pressure checks are vital.

How preeclampsia affects the baby#

In the womb, the baby is attached to a special organ of pregnancy called the placenta. The placenta supplies the baby with oxygen and nutrients from the mother’s blood and removes waste products such as carbon dioxide back into the mother’s blood.

If the mother has preeclampsia, high blood pressure can reduce the oxygen and nutrients reaching the baby. In severe cases the baby can be gradually starved of oxygen and nutrients, which may restrict growth. This growth restriction can threaten the baby’s life, so the baby may need to be born early.

In some cases the placenta separates from the wall of the uterus, and the woman experiences vaginal bleeding and abdominal pain. This is a medical emergency.

Diagnosis#

Preeclampsia is diagnosed when high blood pressure (140/90 mm Hg or higher) occurs together with one or more of the following after 20 weeks of pregnancy:

• Protein in the urine
• Fetal growth restriction, identified by fetal ultrasound
• Other signs that body organs are being affected

Treatment#

If you are diagnosed with mild preeclampsia, your doctor will advise how often you need antenatal check-ups. Your blood pressure and urine will be tested regularly, and you will be asked about any symptoms.

If you are diagnosed with severe preeclampsia, you may need to be admitted to hospital for monitoring and treatment, sometimes until your baby is born. Treatment may include medication to lower blood pressure and anticonvulsant medication to prevent seizures.

At present, the only cure for preeclampsia is for the baby to be born and the placenta to be delivered. In some cases this means that labour is induced.

Effects on the mother#

At its most serious, blood pressure can be very high and other organs can be affected, including the kidneys, liver, brain and blood. If left untreated, preeclampsia can lead to serious problems such as:

• Fitting or convulsions
• Fluid retention, including swelling of the feet and hands
• Dizziness
• Headache
• Visual disturbances

Maternal deaths are very rare, but preeclampsia and its associated complications account for a significant share of the deaths that do occur. Researchers are looking for ways to predict preeclampsia in order to reduce the risks for mothers and babies. Because it tends to run in families, scientists are searching for the gene or genes that may be responsible, in the hope that a pre-pregnancy test may one day be possible.

Key points#

• The causes of preeclampsia are not fully understood, but genetic factors and the placenta seem to play significant roles.
• Preeclampsia tends to be more common in first pregnancies than in later ones.
• Preeclampsia most commonly causes high blood pressure and protein in the urine.
• That is why regular antenatal checks of your blood pressure are so important.
• Early symptoms can include proteinuria (protein in the urine).