Preeclampsia, also written pre-eclampsia, is a condition during pregnancy where there is a sudden, sharp rise in blood pressure, swelling (edema), and albuminuria (excess protein albumin leaks into the urine). Swelling tends to occur in the face, hands, and feet.
Preeclampsia is the most common complication to occur during pregnancy. It generally develops during the third trimester and affects about 1 in 20 pregnancies.
In this article, we will cover various aspects of preeclampsia, its complications, diagnosis, and treatment.
Contents of this article:
Fast facts on preeclampsia
Here are some key points about preeclampsia. More detail and supporting information is in the main article.
- Preeclampsia affects roughly 5 percent of pregnancies
- If preeclampsia is untreated, it can develop into eclampsia, a potentially life-threatening condition
- The exact causes of preeclampsia are not known but are likely to involve blood vessels in the placenta
- Some research implies that there is a genetic component to preeclampsia
- According to one study, traffic pollution might be connected to preeclampsia
What is preeclampsia?
Preeclampsia affects roughly 1 in 20 pregnancies.
Women in their first pregnancy have a higher risk of developing preeclampsia, as do patients with diabetes and mothers carrying twins.
Some women have preeclampsia in every pregnancy; experts are not sure why.
If the preeclampsia remains untreated, it can develop to eclampsia, in which the mother can experience convulsions, coma, and can even die. However, complications from preeclampsia are extremely rare if the mother attends her pre-natal appointments.
Preeclampsia can have some long-term consequences for the developing baby.
Symptoms of preeclampsia
Early signs of preeclampsia include:
- Hypertension (high blood pressure)
- Proteinuria (protein in the urine)
In the majority of cases, the mother will not be aware of these two signs, and will only find out when a healthcare professional picks them up during an antenatal visit.
Although 6-8 percent of all pregnant women experience hypertension, it does not necessarily mean they have preeclampsia. The most telling sign is the presence of protein in the urine.
As the preeclampsia progresses, the mother can experience edema (fluid retention), with swelling in the hands, feet, ankles, and face.
Swelling is a common part of pregnancy, especially during the third trimester, and tends to occur in the lower parts of the body, such as the ankles and feet. Symptoms are usually milder first thing in the morning, and build up during the day. This is not preeclampsia, in which edema occurs suddenly and tends to be much more severe.
Later on, the following signs and symptoms may develop:
- Blurry vision, sometimes seeing flashing lights
- Headaches, often severe
- Pain just below the ribs
- Rapid weight gain (caused by edema)
The main sign of preeclampsia in the fetus is poor growth because the blood supply to the placenta is restricted.
Causes of preeclampsia
Experts are not sure why preeclampsia occurs. Most say that there is a problem with the proper development of the placenta because the blood vessels that supply it are faulty.
How might the placenta affect blood pressure?
Preeclampsia is thought to be due to insufficiently formed placental blood vessels.
The mother's blood supply links to the unborn baby's via the placenta. All the baby's oxygen and nutritional requirements travel through the placenta.
The baby's waste products travel the opposite direction, through the placenta, to the mother.
As the baby grows, the amount of blood that passes through the placenta increases.
In preeclampsia, the food supply to the placenta is inadequate; possibly because the placenta itself has not developed properly during the pregnancy.
This may be because tiny blood vessels in the placenta, called villi, did not develop into arteries as they are supposed to. This hinders the placenta's development because it is not receiving as much blood, and therefore nutrients, as it needs.
If the placenta is not functioning properly, the extra blood supply that should be traveling from mother to child will not get through; this causes hypertension, swelling, and possibly kidney problems. She cannot eliminate waste products fast enough, and they build up in her blood, while certain vital proteins that should stay in the bloodstream leak into her urine, causing proteinuria.
Risk factors of preeclampsia
Risk factors associated with preeclampsia include:
- First pregnancies - the chances of preeclampsia during a first pregnancy are considerably higher than the subsequent ones
- Pregnancy gap - if the second pregnancy occurs at least 10 years after the first, the second pregnancy has a higher risk of preeclampsia
- Family history - a woman whose mother or sister had preeclampsia has a higher risk of developing it herself
- Personal history of preeclampsia - a woman who had preeclampsia in her first pregnancy has a much higher risk of having the same condition in her subsequent pregnancies
- Age - women over 40 and teenagers are more likely to develop preeclampsia compared with other ages
- Certain conditions and illnesses - women with diabetes, hypertension, migraines, and kidney disease are more likely to develop preeclampsia
- Obesity - preeclampsia rates are much higher among obese women
- Multiple pregnancies - if a mother is expecting two or more babies, the risk is higher
A blood test and urine test are both necessary to diagnose preeclampsia.
For a diagnosis of preeclampsia to be made, both of the following tests must come back positive:
Hypertension - the woman's blood pressure is too high. A blood pressure reading above 140/90 mm Hg is abnormal in pregnancy.
Proteinuria - protein is detected in the urine. Urine samples are collected over 12 hours or more, and the amount of protein is assessed. This can give an indication of the severity of the condition.
The doctor may also order further diagnostic tests:
- Blood tests - to see how well the kidneys and the liver are functioning and whether the blood is clotting properly.
- Fetal ultrasound - the baby's progress will be closely monitored to make sure they are growing properly.
- Non-stress test - the doctor checks how the baby's heartbeat reacts when they move. If the heartbeat increases 15 beats or more a minute for at least 15 seconds twice every 20 minutes, it is a sign that everything is probably fine.
Treatment options for preeclampsia
Preeclampsia is not cured until the baby is delivered. Until the mother's blood pressure comes down, she is at a greater risk of stroke, severe bleeding, placental abruption, and seizures. In some cases, especially if the preeclampsia started early, delivery may not be the best option for the fetus.
Women who had preeclampsia in previous pregnancies are advised to attend prenatal sessions more often. The following medications may be recommended:
- Antihypertensives - used to lower blood pressure.
- Anticonvulsants - in severe cases, these drugs are used to prevent a first seizure, the doctor may prescribe magnesium sulfate.
- Corticosteroids - if the mother has preeclampsia or HELLP syndrome (see below), these drugs can improve platelet and liver functioning, which prolongs the pregnancy. They also speed up the development of the baby's lungs, which is important if they are going to be born prematurely - the best treatment for HELLP syndrome is usually to deliver as soon as possible.
If the mother is far from the end of her pregnancy and her symptoms are mild, the doctor may advise her to rest in bed; this helps bring the blood pressure down, which in turn increases the flow of blood to the placenta, which benefits the baby.
Some women are advised to just lie down in bed, and only sit up or stand when they really have to. Others may be allowed to sit on an armchair, sofa, or bed, but will have their physical activities strictly limited. Blood pressure and urine tests will be carried out regularly. The baby will also be monitored closely.
In severe cases, the mother may have to be hospitalized and given continuous bed rest; she will be monitored closely.
If preeclampsia is diagnosed close to the end of the pregnancy, the doctors may advise delivering the baby as soon as possible.
In very severe cases, there may be no choice and either labor is induced, or a C-section is performed as soon as possible. During childbirth, the mother may be given magnesium sulfate to improve uterine blood flow and prevent seizures.
The symptoms of preeclampsia will go away within a few weeks of delivery.
Possible complications of preeclampsia
If preeclampsia is not treated, there is a risk of serious complications. Complications are rare if the mother goes to ante-natal visits. However, if the condition is not diagnosed for some reason, or she continues to smoke, the risks are considerably greater.
The following complications may develop from preeclampsia:
- HELLP syndrome - this can become life-threatening very quickly, for both the mother and the baby. HELLP stands for Hemolysis, Elevated Liver enzymes, and Low Platelet count. It is a combined liver and blood clotting disorder that most commonly occurs straight after giving birth, but can appear at any time after the twentieth week of pregnancy. Very rarely, it may occur beforehand. The only way to treat HELLP syndrome effectively is to deliver the baby as soon as possible.
- Poor blood flow to the placenta - if blood flow to the placenta is restricted, the baby might not be getting essential oxygen and nutrients, which may lead to slower growth, breathing difficulties, and premature birth.
- Placental abruption - the placenta separates from the inner wall of the uterus. In severe cases, there may be heavy bleeding, which can damage the placenta. Any damage to the placenta may place the baby's and mother's life at risk.
- Eclampsia - basically a combination of preeclampsia and seizures (fits). The patient may experience pain under the ribs on the right side of the body, intense headache, blurry vision, confusion, and decreased alertness. If left untreated the patient is at risk of going into a coma, suffering permanent brain damage, and dying. The condition is life-threatening for the baby as well.
- Cardiovascular disease - women who have preeclampsia have a higher risk of developing cardiovascular diseases later in life.