Pre-eclampsia

Pre-eclampsia is a serious blood pressure condition that can develop during pregnancy, typically after the 20th week, affecting 5% to 8% of all pregnancies and posing risks to both mother and baby if left untreated.

Table of contents

• What is pre-eclampsia?
• Signs and symptoms
• Causes and risk factors
• How is pre-eclampsia diagnosed?
• Treatment and management
• Possible complications
• Prevention
• Long-term health impact

What is pre-eclampsia?

Pre-eclampsia is a complication of pregnancy that involves high blood pressure and signs of organ damage, usually affecting the kidneys or liver^[1]. This condition typically begins after 20 weeks of pregnancy in women whose blood pressure had previously been in the normal range^[1]. In some cases, pre-eclampsia can also develop after giving birth, a condition called postpartum pre-eclampsia, which most often occurs within 48 hours of delivery^[5].

Pre-eclampsia is a serious health problem for pregnant people around the world. In the United States, it affects about 1 in every 25 pregnancies^[6]. Globally, pre-eclampsia affects 2% to 8% of pregnancies and is responsible for around 46,000 maternal deaths and about 500,000 fetal or newborn deaths per year^[8]. The condition is also a leading cause of premature deliveries, accounting for about 15% of deliveries before 37 weeks of pregnancy in the U.S.^[3].

The defining features of pre-eclampsia are high blood pressure (hypertension) and proteinuria (high levels of protein in the urine), which indicates kidney damage^[1]. However, pre-eclampsia can also be diagnosed based on high blood pressure combined with other signs of organ problems, such as decreased blood platelets, trouble with the kidneys or liver, fluid in the lungs, or signs of brain problems like seizures or visual disturbances^[12].

Signs and symptoms

Many people with pre-eclampsia do not feel sick and may not notice any symptoms^[5]. The first signs are often detected during routine prenatal visits when a healthcare provider checks blood pressure and urine^[1]. It is unlikely that you will notice early signs like high blood pressure or protein in your urine, but they should be picked up during your regular pregnancy appointments^[4].

When symptoms do develop, they may include:

• Severe headaches that do not go away or become worse^[1]
• Vision problems, such as blurred vision, seeing flashing lights or spots, or sensitivity to light^[1]
• Pain just below the ribs on the right side or in the upper belly^[1]
• Nausea or vomiting, particularly worrisome if it occurs after the first three months of pregnancy^[1]
• Sudden swelling of the face, hands, or feet^[1]
• Shortness of breath, which may be caused by fluid in the lungs^[1]
• Feeling lightheaded or faint^[5]

Some swelling of the feet and ankles is considered normal during pregnancy^[5]. However, sudden weight gain over 1 to 2 days or more than 2 pounds per week can be a warning sign^[5].

In cases of severe pre-eclampsia, additional signs may include very high blood pressure (160/110 mm Hg or higher), decreased kidney or liver function, low blood platelet levels, fluid in the lungs, and producing very little or no urine^[3]. If you experience any symptoms of pre-eclampsia, you should seek medical advice immediately by calling your midwife, doctor’s office, or emergency services^[4].

Causes and risk factors

The exact cause of pre-eclampsia is unknown^[3]. Researchers believe the condition may occur when there is a problem with the placenta, the organ that links the baby’s blood supply to the mother’s^[4]. Pre-eclampsia is thought to start in the placenta when abnormalities develop early in pregnancy, leading to reduced blood flow to the placenta, fetus, and the pregnant woman’s organs^[5].

Some factors that may contribute to the development of pre-eclampsia include problems with blood vessels, autoimmune disorders, genes, and the pregnant person’s diet^[5]. However, no one is entirely sure why some people develop pre-eclampsia while others do not^[3].

Healthcare providers have identified several factors that increase the risk of developing pre-eclampsia. These risk factors are often classified as high risk or moderate risk.

High-risk factors include:

• History of high blood pressure, kidney disease, or diabetes before pregnancy^[3]
• Expecting twins, triplets, or more^[3]
• Autoimmune conditions like lupus or antiphospholipid syndrome^[3]
• Having had pre-eclampsia in a previous pregnancy^[4]

Other factors that can increase your chances of developing pre-eclampsia include:

• A family history of pre-eclampsia^[4]
• Being 40 years old or older, or younger than 18^[5]
• It being more than 10 years since your last pregnancy^[4]
• This being your first pregnancy^[5]
• Having a body mass index (BMI) of 35 or more^[4]
• Being African American or Hispanic^[5]
• Getting pregnant through in-vitro fertilization, especially after a frozen embryo transfer^[5]

If you have two or more of these factors together, your chances of developing pre-eclampsia are higher^[4].

How is pre-eclampsia diagnosed?

Pre-eclampsia is diagnosed based on the presence of high blood pressure and other signs of organ damage after 20 weeks of pregnancy^[8]. A blood pressure reading has two numbers: the first number is the systolic pressure, which measures blood pressure when the heart is contracting, and the second number is the diastolic pressure, which measures blood pressure when the heart is relaxed^[9].

In pregnancy, high blood pressure is diagnosed if the systolic pressure is 140 millimeters of mercury (mm Hg) or higher or if the diastolic pressure is 90 mm Hg or higher^[9]. If you have a high blood pressure reading during an appointment, your healthcare provider will likely take a second reading four hours later to confirm the diagnosis^[9].

If you have high blood pressure, your healthcare provider will order additional tests to check for other signs of pre-eclampsia^[9]. These may include:

• Blood tests to see how well the liver and kidneys are working and to measure blood platelet levels, which are the cells that help blood clot^[9]
• Urine analysis to determine how well the kidneys are working, which may involve collecting urine over 24 hours or providing a single urine sample^[9]
• Fetal ultrasound to monitor the baby’s growth and well-being^[9]
• Electronic monitoring of the baby’s heart rate using a process called cardiotocography, which can detect any stress or distress in the baby^[10]

You often don’t know you have pre-eclampsia until your healthcare provider checks your blood pressure and urine at a prenatal appointment^[3]. This is why it is essential to attend all of your prenatal care visits, even if you are feeling fine^[6].

Treatment and management

The only cure for pre-eclampsia is to deliver the baby^[1]. However, the timing and method of delivery depend on how severe the condition is and how many weeks pregnant you are^[1]. Before delivery, treatment focuses on careful monitoring and medications to lower blood pressure and manage complications^[1].

If you are diagnosed with pre-eclampsia, you should be referred to a hospital specialist for further assessment and any necessary treatment^[4]. You may be able to return home afterwards and attend regular follow-up appointments, possibly daily^[4]. However, you may be admitted to hospital for monitoring and treatment if there are any concerns for you or your baby^[4].

For mild pre-eclampsia: If your baby is not fully developed and you have mild pre-eclampsia, the disease can often be managed at home until your baby has matured^[5]. This requires frequent doctor visits, monitoring blood pressure at home if your doctor asks you to, and possibly taking medications to lower your blood pressure^[5]. The severity of pre-eclampsia can change quickly, so very careful follow-up is needed^[5].

For severe pre-eclampsia: If the condition becomes more severe, hospitalization may be necessary for closer monitoring of both mother and baby^[10]. Treatment in the hospital may include medications to control blood pressure and prevent seizures and other complications, as well as steroid injections for pregnancies under 34 weeks to help speed up the development of the baby’s lungs^[5].

Medications: Medicine is recommended to help lower blood pressure and reduce the likelihood of serious complications, such as stroke^[10]. Some medicines commonly used in the UK include labetalol, nifedipine, or methyldopa^[10]. Anticonvulsant medicine, such as magnesium sulfate, may be prescribed to prevent or treat seizures^[10]. Magnesium sulfate reduces the risk of eclampsia (seizures) by more than half^[8].

Delivery: In most cases of pre-eclampsia, having your baby at about the 37th to 38th week of pregnancy is recommended^[1]. This may mean that labor needs to be started artificially (induced labor) or you may need to have a caesarean section^[10]. If your condition becomes more severe before 37 weeks and there are serious concerns about your health or your baby’s health, earlier delivery may be necessary^[10].

After delivery, pre-eclampsia usually improves soon after your baby is born^[10]. However, you may need to stay in hospital after the birth so you can be monitored, and your blood pressure will be measured regularly^[10]. You may need to continue taking medicine to lower your blood pressure for several weeks^[10].

Possible complications

Pre-eclampsia can be dangerous for both the pregnant person and the developing baby^[3]. When left untreated, pre-eclampsia can lead to serious, even life-threatening complications^[1].

Complications for the mother may include:

• Eclampsia, which involves seizures that can be life-threatening for the mother and baby^[4]
• Stroke, particularly during pregnancy and after delivery^[2]
• Kidney or liver damage^[3]
• Fluid buildup in the lungs, making it difficult to breathe^[3]
• Problems with blood clotting^[5]
• HELLP syndrome, a severe form of pre-eclampsia involving Hemolysis (destruction of red blood cells), Elevated Liver enzymes (showing liver problems), and Low Platelets (cells responsible for clotting)^[2]
• Maternal death^[8]

Complications for the baby may include:

• The placenta detaching from the uterine wall (abruption)^[3]
• Slowed growth of the fetus due to fewer nutrients traveling through the umbilical cord^[3]
• Decreased levels of amniotic fluid surrounding the baby in the uterus^[3]
• Premature delivery (before 37 weeks) to prevent severe complications for the pregnant person or the fetus^[3]
• Fetal death^[8]

In parts of the world with limited medical care, pre-eclampsia and eclampsia cause many women to die during pregnancy^[2]. Pre-eclampsia and eclampsia are responsible for approximately 10% of maternal deaths in Asia and Africa, and 25% in Latin America^[8]. Fortunately, with appropriate prenatal care and monitoring, most women with pre-eclampsia and their babies survive^[2].

Prevention

If you are at high risk for pre-eclampsia, your healthcare provider may want you to take low-dose aspirin during your pregnancy to help prevent it^[6]. Low-dose aspirin can reduce the risk of pre-eclampsia and should be started ideally before 16 weeks of pregnancy, but can be started any time between 12 weeks and 28 weeks of pregnancy until giving birth^[6].

If you are thought to be at high risk of developing pre-eclampsia, you may be advised to take a 75 to 150 mg daily dose of aspirin from the 12th week of pregnancy until your baby is born^[4]. It is important that you take low-dose aspirin exactly as your provider recommends it^[6].

Other steps to help reduce your risk include:

• Attending all prenatal care appointments for regular blood pressure and urine checks^[3]
• Gaining a healthy amount of weight during pregnancy as recommended by your healthcare provider^[5]
• Not using tobacco or tobacco-like products, including cannabis and other substances, as they can harm your health and your baby’s development^[19]
• Monitoring your blood pressure at home if your doctor or midwife asks you to^[19]
• Checking your baby’s movements once each day^[19]

Long-term health impact

Pre-eclampsia can have a long-lasting impact on maternal health, even after pregnancy^[20]. Both the American College of Cardiology and the American Heart Association list pre-eclampsia as a major risk factor for cardiovascular disease, even far in the future^[20].

Women who have had pre-eclampsia are at least twice as likely to have heart disease later in life^[20]. They have an increased risk of chronic high blood pressure, stroke, heart failure, heart attack, and peripheral vascular disease^[20]. Cardiovascular disease is responsible for one in five deaths in women in the United States—more than any other cause, including deaths from all types of cancer combined^[20].

Pre-eclampsia should now be considered a “red flag” diagnosis that indicates the need for earlier cardiovascular risk factor assessment, which typically may not be pursued until later in life^[20]. Patients diagnosed with pre-eclampsia would likely benefit from earlier cardiovascular risk factor screening, including checking cholesterol levels and markers of type 2 diabetes and other diseases, within a year after delivery^[20].

You should be offered a postnatal appointment 6 to 8 weeks after your baby is born to check your progress and discuss any concerns^[10]. Your healthcare provider can help you understand your long-term health risks and develop a plan for monitoring and maintaining your health in the years after pregnancy.