Preeclampsia

What happens in preeclampsia

Preeclampsia starts with the placenta. In early pregnancy, the blood vessels that supply the placenta do not remodel properly, so the placenta is poorly supplied with blood. The stressed placenta releases substances (including sFlt-1, an anti-angiogenic factor) into the mother's blood that damage the lining of blood vessels throughout the body. This leads to:

• high blood pressure
• leaky blood vessels and swelling
• protein in the urine from kidney damage
• liver inflammation
• low platelets and clotting problems
• brain irritability and seizure risk
• reduced blood flow to the baby

Diagnosis criteria

Preeclampsia is diagnosed when, after 20 weeks:

• blood pressure is 140/90 mmHg or higher on two occasions at least 4 hours apart, and
• there is protein in the urine, or, without protein, any of: - low platelets - abnormal liver tests - kidney dysfunction - fluid in the lungs - new headache or vision changes

Preeclampsia with severe features includes blood pressure of 160/110 or higher, severe headache, vision changes, severe upper abdominal pain, fluid in the lungs or significant lab abnormalities.

Related conditions

Risk factors

High risk

• preeclampsia in a previous pregnancy
• chronic high blood pressure
• type 1 or type 2 diabetes
• kidney disease
• autoimmune disease such as lupus or antiphospholipid syndrome
• twins or more

Moderate risk

• first pregnancy
• BMI over 30
• family history of preeclampsia
• age 35 or older
• Black race (reflecting social and structural factors)
• low income
• IVF pregnancy
• more than 10 years since the last pregnancy
• previous low birth weight baby or adverse pregnancy outcome

Symptoms

Preeclampsia can be silent, which is why blood pressure and urine are checked at every visit. Symptoms may include:

• headache that does not go away with acetaminophen
• vision changes: blurring, flashing lights, light sensitivity
• pain under the ribs on the right or in the upper middle belly
• nausea or vomiting in the second half of pregnancy
• sudden swelling of the face, hands or feet, or weight gain of more than 2 to 5 lb (1 to 2 kg) in a week
• shortness of breath
• confusion or feeling something is wrong

Tests

• blood pressure measurements
• urine protein (protein-to-creatinine ratio or 24-hour collection)
• blood count, liver enzymes, kidney function
• ultrasound of the baby's growth and Doppler studies of blood flow
• fetal heart monitoring
• sFlt-1/PlGF blood test in some settings to help predict short-term risk

Treatment

Delivery

Delivery of the baby and placenta is the only cure. Timing balances risks to mother and baby:

• without severe features: close monitoring and delivery at 37 weeks
• with severe features: delivery at 34 weeks or sooner if the mother or baby is unstable. Earlier, care may be prolonged in hospital for a short time with close monitoring

Medicines

• blood pressure medicines: labetalol, nifedipine or hydralazine for severe readings. Oral treatment for ongoing high blood pressure
• magnesium sulfate: given during labor and after birth for severe features to prevent seizures
• corticosteroids before 34 weeks to mature the baby's lungs if early delivery is likely

After birth

Blood pressure often rises again 3 to 6 days after delivery. Checks within 72 hours and again around 7 to 10 days after discharge are recommended. Many people need blood pressure medicine for a few weeks.

Prevention

• low-dose aspirin (81 mg daily) from 12 weeks (ideally before 16 weeks) until delivery for people with one high-risk factor or more than one moderate-risk factor, as recommended by ACOG and the USPSTF
• calcium supplements for people with low dietary calcium
• managing chronic conditions before pregnancy
• attending all prenatal appointments

Long-term health

Preeclampsia is a warning sign for future heart health. It roughly doubles the long-term risk of heart disease and stroke and raises the risk of chronic high blood pressure and kidney disease. Yearly checks of blood pressure, cholesterol, blood sugar and weight are recommended. Recurrence in a future pregnancy is possible.

Frequently asked questions

What are the early signs of preeclampsia?

Often the earliest sign is high blood pressure at a prenatal visit, sometimes with protein in the urine. Symptoms such as persistent headache, vision changes, upper right belly pain, nausea and sudden swelling may follow, though many people feel well at first.

What causes preeclampsia?

It starts with abnormal development of the blood vessels supplying the placenta. The stressed placenta releases substances that damage blood vessels throughout the mother's body, raising blood pressure and affecting the kidneys, liver and brain.

Can preeclampsia happen after giving birth?

Yes. Postpartum preeclampsia can develop up to 6 weeks after delivery, most often within the first week, even after a normal pregnancy. Severe headache, vision changes or breathlessness after birth need urgent care.

Can aspirin prevent preeclampsia?

Low-dose aspirin, started between 12 and 16 weeks, lowers the risk of preeclampsia in people at high risk. Ask your prenatal care provider whether it is recommended for you. Do not start it without advice.

Does preeclampsia affect the baby?

It can reduce blood flow to the placenta, causing slow growth, low amniotic fluid, placental abruption and early delivery. Close monitoring with ultrasound and fetal heart checks helps decide the safest time for delivery.