Preeclampsia is the most common complication to occur during pregnancy. It generally develops during the third trimester and affects about 1 in 20 pregnancies.
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 prenatal appointments.
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.
Symptoms of preeclampsia
Preeclampsia affects roughly 1 in 20 pregnancies.
Initially, preeclampsia may present no symptoms; however, early signs, include:
- high blood pressure (hypertension)
- protein in the urine (proteinuria)
In the majority of cases, the woman will not be aware of these two signs, and will only find out when a doctor observes her during an antenatal visit.
Although 6-8 percent of all pregnant women experience high blood pressure, 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 woman may experience fluid retention (edema), 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 typically 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
- shortness of breath
- pain just below the ribs on the right side
- rapid weight gain (caused by fluid retention)
- decrease in urine output
- decrease in platelets in the blood
- impaired liver function
The main sign of preeclampsia in the fetus is growth restriction due to decreased blood supply to the placenta.
Causes of preeclampsia
Preeclampsia is thought to be due to insufficiently formed placental blood vessels.
Experts are not sure why preeclampsia occurs. Most say that there is a problem with the development of the placenta because the blood vessels that supply it are narrower than normal and respond differently to hormonal signals.
Because the blood vessels are narrower than normal, blood flow is limited.
Why the blood vessels develop differently is not fully understood, but a number of factors may play a role; including:
- damage to the blood vessels
- insufficient blood flow to the uterus
- immune system problems
- genetic factors
Preeclampsia risk factors
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 an increased risk of preeclampsia.
- New paternity. Each pregnancy with a new partner raises the risk of preeclampsia when compared with a second or third pregnancy with the same partner.
- 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 greater risk of having the same condition in her subsequent pregnancies.
- Age. Women over 40 and teenagers are more likely to develop preeclampsia compared with women of other ages.
- Certain conditions and illnesses. Women with diabetes, high blood pressure, migraines, and kidney disease are more likely to develop preeclampsia.
- Obesity. Preeclampsia rates are much higher among obese women.
- Multiple pregnancies. If a woman 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:
The woman's blood pressure is too high. A blood pressure reading above 140/90 millimeters of mercury is abnormal in pregnancy.
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 an indication that everything is normal.
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 (placenta separates from the uterus), 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: These are 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 woman is far from the end of her pregnancy and her symptoms are mild, the doctor may advise her to rest in bed. Resting 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 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 woman may have to be hospitalized and given continuous bed rest where 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 cesarean delivery 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 should go away within a few weeks of delivery.
Preeclampsia and complications
If preeclampsia is not treated, there is a risk of serious complications. Complications are rare if the woman goes to antenatal appointments. However, if the condition is not diagnosed for some reason, the risks are considerably greater.
The following complications may develop from preeclampsia:
HELLP syndrome: HELLP can become life-threatening very quickly, for both the mother and the baby. It stands for hemolysis, elevated liver enzymes, and low platelet count. It is a combined liver and blood clotting disorder that most commonly occurs right after giving birth, but can appear at any time after the 20th 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 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. The woman may experience pain under the ribs on the right side of her body, intense headache, blurry vision, confusion, and decreased alertness. If left untreated the woman 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.
Preeclampsia can have some long-term consequences for the developing baby. Research has shown that high blood pressure in pregnant women may affect the baby's cognitive skills, which can carry through into later life.