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What is pre-eclampsia?
Pre-eclampsia is one of the most common serious complications of pregnancy. In Australia, it is thought to affect around 5-10% of all pregnancies. Of these, 1-2% of cases are severe and can threaten the lives of the mother and her baby. 
The main features of pre-eclampsia are high blood pressure and protein in the urine (proteinuria). These may not cause any noticeable symptoms, but are generally detected by a doctor in a regular check-up during your pregnancy.
Signs and symptoms
Pre-eclampsia usually develops during the second half of pregnancy, but may sometimes develop shortly after giving birth. The main signs of pre-eclampsia are a sudden increase in blood pressure (hypertension) and the presence of protein in the urine, known as proteinuria, which develops during pregnancy. These symptoms can occur without any noticeable effect on the mother, so it is very important for women to have regular check-ups during pregnancy.
Pre-eclampsia can also lead to excess fluid retention, which may appear as swelling, particularly in the hands, feet and face. Some swelling is common in a normal pregnancy, so it can sometimes be difficult to tell whether swelling is a result of pre-eclampsia.
In severe cases of pre-eclampsia, the symptoms can include:
- Nausea and vomiting;
- Blurry vision, or vision of flashing lights, and;
- Pain in the abdomen.
Causes and risk factors
The placenta plays the central role in development of pre-eclampsia. The placenta is a specialised organ that develops in a woman's uterus during pregnancy and transfers nutrients and oxygen from the mother to the baby so that the baby can grow and develop. Women with conditions such as a molar pregnancy, where the placenta develops but the fetus does not, can still develop pre-eclampsia.
In pre-eclampsia, the blood vessels within the placenta do not form normally, due to unclear immune factors, inherited causes and other unknown reasons. This results in a reduced supply of nutrients and oxygen to the fetus. This undersupply causes the placenta to release chemicals in an attempt to restore normal blood flow. These chemicals affect the kidney, liver and other organs in the mother, which cause the signs and symptoms of pre-eclampsia, such as liver failure and brain swelling.
There are several factors that can increase your risk of developing pre-eclampsia during pregnancy. You are more likely to develop pre-eclampsia if you:
Methods for diagnosis
Pre-eclampsia is usually detected in a routine check-up during pregnancy. During this check-up your doctor will measure your blood pressure. If you have a high blood pressure reading and pre-eclampsia is suspected, your doctor may also carry out some other tests to monitor your condition and make sure your baby is healthy.
Your doctor may request a sample of your urine to measure protein levels. This is known as a urinalysis. Having protein in your urine may be a sign of pre-eclampsia. If the analysis is positive for protein, your doctor may request further tests.
Your doctor may also collect a blood sample to test your kidney and liver function, and assess blood cell counts, which can be abnormal in pre-eclampsia.
Your doctor may conduct an ultrasound to assess that your baby is healthy.
Types of treatment
If you have pre-eclampsia, you will need to have your blood pressure monitored closely for the rest of your pregnancy. The treatment you need will usually depend on how far along your pregnancy is and how serious your condition is.
If you have mild pre-eclampsia, your doctor may recommend that you stay off your feet and get lots of rest. This may help improve the blood flow to the placenta and help prevent any complications.
In some cases, antihypertension medications, such as labetalol or methyldopa, can be used to help control blood pressure and prevent complications. If your blood pressure is very high, you may be admitted to hospital so that it can be monitored closely.
If you have pre-eclampsia and your blood pressure is not well controlled by medication, your doctor may recommend delivering your baby early by caesarean section or induced labour. This will generally depend on how far along you are with your pregnancy and how severe your doctor has assessed the pre-eclampsia to be. Delivering the baby - and the placenta - is the only way to cure pre-eclampsia.
Pre-eclampsia can sometimes develop into eclampsia, which is a serious condition that causes the mother to have seizures during her pregnancy, or within a short time after giving birth. These seizures can result in a coma, brain damage, or death for the mother or baby.
Magnesium sulfate is a type of medication that is given to a mother with severe pre-eclampsia to reduce the risk of these seizures. It is not very common for pre-eclampsia to progress to eclampsia, if it is detected and treated early.
HELLP syndrome is a serious complication that can develop in severe cases of pre-eclampsia. It can lead to damage of the mother's liver, a breakdown of her red blood cells and lower platelet counts. Symptoms of HELLP syndrome include headache, nausea, vomiting, abdominal pain, swelling and changes in vision. These are very similar to the symptoms of pre-eclampsia.
Reduced blood flow to the placenta
During pregnancy, a baby receives oxygen and nutrients from the placenta, which allows normal growth and development. Pre-eclampsia can reduce the flow of blood to the placenta. In some cases this means that the baby does not get enough oxygen or nutrients, which affects its development. Babies may be born smaller in size, born early and/or with other complications.
Pre-eclampsia can sometimes lead to placental abruption, which occurs when the placenta separates from the wall of the uterus. This can cause abdominal or lower back pain and vaginal bleeding. In severe cases, placental abruption can prevent the baby getting enough oxygen and nutrients, and be life-threatening for both the mother and her baby.
The signs of pre-eclampsia usually go away shortly after giving birth. If it is left untreated, pre-eclampsia can lead to serious complications and can threaten the life of the mother and her baby.
There is no known way to prevent pre-eclampsia. Regular check-ups with your doctor during pregnancy may help to detect and treat the condition early, which is the best way to prevent serious complications. If you have a high risk of developing pre-eclampsia, your doctor may recommend taking low doses of aspirin during pregnancy to reduce the risk.