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Preeclampsia is a pregnancy complication characterized by high blood pressure and signs of damage to another organ system, most often the liver and kidneys. Preeclampsia usually begins after 20 weeks of pregnancy in women whose blood pressure had been normal. Left untreated, preeclampsia can lead to serious—even fatal—complications for both mother and the baby. In preeclampsia, the most effective treatment is delivery of the baby. Even after delivering the baby, it can still take a while for the mother to get better.
If preeclampsia is diagnosed too early in pregnancy, and we need to deliver the baby, it is a challenging task. The baby needs more time to mature, but we need to avoid putting the mother or her baby at risk of serious complications. Rarely, preeclampsia develops after delivery of a baby, a condition known as postpartum preeclampsia.
Symptoms
Preeclampsia sometimes develops without any symptoms. High blood pressure may develop slowly, or it may have a sudden onset. The first sign of preeclampsia is, commonly, a rise in blood pressure. Blood pressure that exceeds 140/90 mm Hg or greater—documented on two occasions, at least four hours apart—is abnormal.
Other signs and symptoms of preeclampsia may include:
• Excess protein in urine (proteinuria) or additional signs of kidney problems
• Severe headaches
• Changes in vision, including temporary loss of vision, blurred vision, or light sensitivity
• Upper abdominal pain, usually under the ribs on the right side
• Nausea or vomiting
• Decreased urine output
• Decreased levels of platelets in blood (thrombocytopenia)
• Impaired liver function
• Shortness of breath, caused by fluid in the lungs
• Sudden weight gain and swelling (edema)—particularly in the face and hands—may occur with preeclampsia. But these also occur in many normal pregnancies, so they’re not considered reliable signs of preeclampsia.
When to see a doctor
Regular prenatal visits are important so that blood pressure can be monitored. The mother should contact her doctor immediately or go to an emergency room if she has severe headache, blurred vision, or other visual disturbance, severe pain in her abdomen, or severe shortness of breath.
Because headache, nausea, and aches and pains are common pregnancy complaints, it’s difficult to know when new symptoms are simply part of being pregnant and when they may indicate a serious problem, especially if it’s the first pregnancy. She should contact her doctor in case of any concerning symptom.
Causes
The exact cause of preeclampsia involves several factors. Experts believe it begins in the placenta— the organ that nourishes the fetus throughout pregnancy. Early in pregnancy, new blood vessels develop and evolve to efficiently send blood to the placenta. In women with preeclampsia, these blood vessels don’t seem to develop or function properly. They are narrower than normal blood vessels and react differently to hormonal signaling, which limits the amount of blood that can flow through them.
Causes of this abnormal development may include:
• Insufficient blood flow to the uterus
• Damage to the blood vessels
• A problem with the immune system
• Certain genes
• Other high blood pressure disorders during pregnancy
Preeclampsia is classified as one of four high blood pressure disorders that can occur during pregnancy. The other three are:
Gestational hypertension: Women with gestational hypertension have high blood pressure but no excess protein in their urine or other signs of organ damage. Some women with gestational hypertension eventually develop preeclampsia.
Chronic hypertension: Chronic hypertension is high blood pressure that was present before pregnancy or that occurs before 20 weeks of pregnancy. But because high blood pressure usually doesn’t have symptoms, it may be hard to determine when it began.
Chronic hypertension with superimposed preeclampsia: This condition occurs in women who have been diagnosed with chronic high blood pressure before pregnancy, but then develop worsening high blood pressure and protein in the urine or other health complications during pregnancy.
Risk factors
Preeclampsia develops only as a complication of pregnancy. Risk factors include:
History of preeclampsia: A personal or family history of preeclampsia significantly raises the risk of preeclampsia.
Chronic hypertension: If she already has chronic hypertension, she has a higher risk of developing preeclampsia.
First pregnancy: The risk of developing preeclampsia is highest during the first pregnancy.
New paternity: Each pregnancy with a new partner increases the risk of preeclampsia more than does a second or third pregnancy with the same partner.
Age: The risk of preeclampsia is higher for very young pregnant women as well as pregnant women older than 35.
Race: Black women have a higher risk of developing preeclampsia than women of other races.
Obesity: The risk of preeclampsia is higher in the obese.
Multiple pregnancy: Preeclampsia is more common in women who are carrying twins, triplets, or other multiples.
Interval between pregnancies: Having babies less than two years or more than 10 years apart leads to a higher risk of preeclampsia.
History of certain conditions: Chronic high blood pressure, migraines, type 1 or type 2 diabetes, kidney disease, a tendency to develop blood clots, or lupus increase the risk of preeclampsia in pregnancy.
In vitro fertilization: Risk of preeclampsia is increased if the baby was conceived with in vitro fertilization.
Complications
If preeclampsia is severe and it occurs earlier in pregnancy, the risks are greater for the mother and baby. Preeclampsia may require induced labor and delivery. Delivery by cesarean delivery (C-section) may be necessary if there are clinical or obstetric conditions that require a speedy delivery. Otherwise, a scheduled vaginal delivery is recommended.
Complications of preeclampsia may include:
Fetal growth restriction: Preeclampsia affects the arteries carrying blood to the placenta. If the placenta doesn’t get enough blood, the baby may receive inadequate blood and oxygen and fewer nutrients. This can lead to slow growth known as fetal growth restriction or low birth weight.
Preterm birth: If preeclampsia is severe, early delivery may be indicated to save the life of the mother and baby. Prematurity can lead to breathing and other problems for the baby.
Placental abruption: It is a condition in which the placenta separates from the inner wall of the uterus before delivery. Severe abruption can cause heavy bleeding, which can be life-threatening for both mother and baby.
HELLP syndrome: HELLP—which stands for hemolysis (the destruction of red blood cells), elevated liver enzymes, and low platelet count—syndrome is a more severe form of preeclampsia, and can rapidly become life-threatening for both mother and baby. Symptoms of HELLP syndrome include nausea and vomiting, headache, and upper right abdominal pain. HELLP syndrome is particularly dangerous, because it represents damage to several organ systems. On occasion, it may develop suddenly, even before high blood pressure is detected, or it may develop without any symptoms at all.
Eclampsia: When preeclampsia isn’t controlled, eclampsia—which is essentially preeclampsia plus seizures—can develop. It is very difficult to predict which patients will have preeclampsia that is severe enough to result in eclampsia. Often, there are no symptoms or warning signs to predict eclampsia. Because eclampsia can have serious consequences for both mother and baby, delivery becomes necessary, regardless of how far along the pregnancy is.
Other organ damage: Preeclampsia may result in damage to the kidneys, liver, lung, heart, or eyes, and may cause a stroke or other brain injury. The amount of injury to other organs depends on the severity of preeclampsia.
Cardiovascular disease: Having preeclampsia may increase the risk of future heart and blood vessel (cardiovascular) disease in the mother. The risk is even greater if she had preeclampsia more than once, or she had a preterm delivery. To minimize this risk, after delivery, she should try to maintain her ideal weight, eat a variety of fruits and vegetables, exercise regularly, and never smoke.
Prevention
Researchers continue to study ways to prevent preeclampsia, but so far, no clear strategies have emerged. Eating less salt, changing activities, restricting calories, or consuming garlic or fish oil doesn’t reduce the risk. Increasing intake of vitamins C and E hasn’t been shown to have a benefit.
Some studies have reported an association between vitamin D deficiency and an increased risk of preeclampsia. But, while some studies have shown an association between taking vitamin D supplements and a lower risk of preeclampsia, others have failed to make the connection.
In certain cases, however, we may be able to reduce the risk of preeclampsia with:
Low-dose aspirin: If there are certain risk factors—including a history of preeclampsia, a multiple pregnancy, chronic high blood pressure, kidney disease, diabetes, or autoimmune disease—a daily low-dose aspirin may be started after 12 weeks of pregnancy.
Calcium supplements: In some populations, women who have calcium deficiency before pregnancy—and who don’t get enough calcium during pregnancy through their diets— might benefit from calcium supplements to prevent preeclampsia.
Before becoming pregnant, especially if there is a history of preeclampsia before, it’s good to lose weight if needed, and make sure other conditions, such as diabetes, are well-managed. Once pregnant, early and regular prenatal care is important. If preeclampsia is detected early, we may be able to prevent complications and make the best choices for the mother and her baby.
