Preeclampsia is a serious blood-pressure disorder that can develop during pregnancy, usually after 20 weeks, and occasionally in the days or weeks after delivery. It is easy to miss because it often causes no symptoms at first and is picked up only when a routine prenatal visit turns up high blood pressure or protein in the urine. Left unrecognized, though, preeclampsia can strain the liver, kidneys, brain, and blood, and it remains one of the leading causes of serious illness for pregnant people and their babies worldwide. This guide explains what preeclampsia is, how to recognize its warning signs, what causes it, how doctors diagnose it with blood-pressure readings and blood and urine tests, and what today’s treatment, prevention, and research have to offer.
What is preeclampsia?
Preeclampsia is defined as new-onset high blood pressure, generally a reading of 140/90 mmHg or higher, that appears after the 20th week of pregnancy in a person whose blood pressure was previously normal. High blood pressure alone is not enough for the diagnosis. It must be paired with either protein in the urine or another sign that the condition is affecting an organ, such as a low platelet count, impaired liver or kidney function, fluid building up in the lungs, or new headaches and visual symptoms. Because chronic hypertension is one of its strongest risk factors, it helps to understand the high blood pressure symptoms, causes, and treatments covered in this guide alongside the pregnancy-specific picture below.
Most preeclampsia develops in the third trimester, but it can begin earlier, and a form called postpartum preeclampsia can appear after the baby is born, most often within the first few days to a week of delivery. Blood pressure of 160/110 mmHg or higher, or the involvement of organs beyond the kidneys, marks the condition as severe and calls for urgent care. Understanding where a person falls on that spectrum shapes every decision that follows, from how closely they are monitored to when their baby is delivered.
Symptoms of preeclampsia
One of the most important things to know about preeclampsia is that it is frequently silent. Many people feel completely well and learn they have it only because a prenatal check finds elevated blood pressure or protein in a urine sample. That is precisely why regular prenatal visits matter so much, since they catch the condition before it announces itself.
When warning signs do appear, they tend to reflect rising blood pressure and stress on the organs. A severe or persistent headache that does not ease with usual remedies, changes in vision such as blurring or flashing lights, and pain in the upper right abdomen or just under the ribs are especially important to report. Sudden swelling of the face and hands, rapid weight gain over a few days, nausea or vomiting that starts late in pregnancy, and shortness of breath can also signal trouble. Any of these symptoms in the second half of pregnancy deserves a prompt call to an obstetric provider rather than a wait-and-see approach.
| Warning sign | What it can feel like |
|---|---|
| Severe or persistent headache | A pounding or constant head pain that does not settle with rest or usual pain relief |
| Vision changes | Blurred sight, flashing lights, dark spots, or brief loss of vision |
| Upper abdominal pain | Aching or sharp pain below the ribs, most often on the right side under the liver |
| Sudden swelling | Puffiness of the face and hands, sometimes with fast weight gain from fluid |
| Shortness of breath | Difficulty breathing, which can reflect fluid collecting in the lungs |
| Nausea or vomiting | New queasiness or vomiting that begins in the second half of pregnancy |
Causes and risk factors of preeclampsia
The root of preeclampsia lies in the placenta, the organ that connects a pregnant person to the developing baby. Early in pregnancy, the placenta forms a network of blood vessels that should widen to carry a growing supply of blood. In preeclampsia, those vessels develop abnormally and deliver less blood than they should. The stressed placenta then releases proteins into the mother’s bloodstream that damage the lining of her blood vessels, raising blood pressure and disturbing the kidneys, liver, and other organs. Researchers describe this as an imbalance between an anti-angiogenic protein called sFlt-1 and a pro-angiogenic protein called PlGF, and that imbalance is now the basis of a blood test used to help predict the disease.
No single cause explains every case, but several factors raise the odds. A first pregnancy, a history of preeclampsia in an earlier pregnancy, and carrying more than one baby all increase risk, as does becoming pregnant through in vitro fertilization. Chronic health conditions matter a great deal too. It can help to review the diabetes symptoms, causes, and treatments explained in this guide and to read this overview of chronic kidney disease symptoms, causes, and treatments, since both conditions, along with chronic high blood pressure, obesity, autoimmune disease, and being older than 35, are among the recognized risk factors.
Preeclampsia, eclampsia, and HELLP syndrome
Preeclampsia sits on a spectrum, and its greatest danger is how quickly it can escalate. When the condition progresses to seizures, it becomes eclampsia, a medical emergency that threatens both mother and baby. Some people have no dramatic warning before a seizure, which is one reason severe preeclampsia is treated so aggressively.
A second severe form is HELLP syndrome, a name that stands for hemolysis, elevated liver enzymes, and low platelets. HELLP reflects damage to red blood cells, the liver, and the clotting system, and it can develop rapidly, sometimes with upper abdominal pain and nausea rather than very high blood pressure. Both eclampsia and HELLP are reasons that clinicians monitor blood tests closely and often move toward delivery when severe disease appears.
How preeclampsia is diagnosed
Diagnosing preeclampsia begins with the two simple checks done at every prenatal visit: a blood-pressure measurement and a urine test for protein. Two elevated readings at least four hours apart, together with protein in the urine, meet the classic definition. When protein is uncertain, laboratories can measure a urine protein-to-creatinine ratio or collect urine over 24 hours to quantify it precisely. This is where laboratory testing becomes central, because blood work reveals organ involvement that a blood-pressure cuff cannot.
A panel of blood tests tells clinicians how the condition is affecting the body, and each result adds a piece to the picture. It helps to understand what a platelet count reveals on a blood test, because a falling count is a hallmark of severe disease and HELLP syndrome. Rising liver enzymes point to liver stress, and you can review what the AST liver enzyme test measures and its normal range to see why it is tracked. Kidney function is followed too, so it is worth seeing what a creatinine test shows about how well the kidneys are working, and clinicians often check uric acid as well, since it can help to understand what uric acid levels indicate on a blood test in a pregnancy complicated by high blood pressure. Doctors may also measure lactate dehydrogenase, a marker of cell injury, and increasingly use the sFlt-1/PlGF ratio, a blood test cleared by the U.S. Food and Drug Administration to help predict which people with a hypertensive disorder of pregnancy will go on to develop preeclampsia with severe features.
| Test | What it measures | Why it matters in preeclampsia |
|---|---|---|
| Blood pressure | The pressure in the arteries, taken with a cuff | A reading of 140/90 mmHg or higher on two occasions is the starting point for diagnosis |
| Urine protein | Protein leaking into the urine, by dipstick, protein-to-creatinine ratio, or 24-hour collection | Signals that the kidneys are affected, a core feature of the condition |
| Platelet count | The number of clotting cells in the blood | A low count points to severe disease or HELLP syndrome |
| Liver enzymes (AST, ALT) | Proteins released when liver cells are stressed | Elevated levels indicate liver involvement |
| Creatinine and uric acid | Waste products cleared by the kidneys | Rising values suggest the kidneys are struggling |
| sFlt-1/PlGF ratio | The balance of two placental proteins in the blood | Helps predict who will progress to severe preeclampsia |
Treatment and management of preeclampsia
The only definitive cure for preeclampsia is delivery of the baby and the placenta, because the placenta is what drives the disease. Timing that delivery is a careful balance. When preeclampsia is mild and the pregnancy is close to term, clinicians often plan delivery around 37 weeks. When it appears earlier, they weigh the risks of prematurity against the danger of letting the condition worsen, and they may aim to gain time under close observation.
Until delivery, management focuses on protecting the mother and buying the baby time to mature. Blood-pressure medicines considered safe in pregnancy, such as labetalol, nifedipine, and hydralazine, are used to bring dangerous readings down. Intravenous magnesium sulfate is given to prevent or treat the seizures of eclampsia, and it is a mainstay in severe disease. If an early delivery seems likely, a course of corticosteroids can speed the maturing of the baby’s lungs. Throughout, the pregnant person is watched closely with repeated blood-pressure checks, blood tests, and monitoring of the baby’s growth and well-being. Anyone with preeclampsia should have a clear plan with their care team about which symptoms mean they need to be seen right away.
Prevention of preeclampsia
Preeclampsia cannot always be prevented, but the risk can be lowered for many people. For those at high risk, major U.S. guidelines from the United States Preventive Services Task Force and the American College of Obstetricians and Gynecologists recommend low-dose aspirin, usually 81 mg a day, started between 12 and 28 weeks of pregnancy and ideally before 16 weeks. Aspirin is thought to improve blood flow through the placenta and has been shown to reduce the chance of developing the condition in people at elevated risk.
Calcium supplementation can help lower risk in populations whose diets are low in calcium. Beyond medication, managing chronic conditions before and during pregnancy, attending every prenatal visit, and keeping blood pressure and weight in a healthy range all support a safer pregnancy. Anyone with risk factors should talk with their obstetric provider early about whether aspirin or other steps are right for them, since prevention works best when it starts in the first half of pregnancy.
Complications and long-term outlook
Most people with preeclampsia who receive prompt care go on to recover fully after delivery, but the condition can cause serious complications when it is severe or untreated. For the mother, these include eclampsia, HELLP syndrome, and damage to the kidneys and liver. Very high blood pressure can also lead to bleeding in the brain, and understanding how that emergency unfolds is easier after you read this guide to stroke symptoms, causes, and treatments. The placenta can separate from the wall of the uterus too, a dangerous event called placental abruption.
For the baby, the main risks come from the need to deliver early and from reduced blood flow through the placenta, which can slow growth. Preterm birth and low birth weight are the most common consequences. The effects can reach beyond pregnancy as well: people who have had preeclampsia carry a higher long-term risk of high blood pressure, heart disease, and stroke, which is why many benefit from ongoing cardiovascular follow-up in the years after delivery.
Latest scientific advances in preeclampsia research
Much of the recent progress in preeclampsia has come from blood tests that can flag the disease before symptoms appear. A 2025 systematic review and meta-analysis pooled data from many studies and found that the sFlt-1/PlGF ratio predicted preeclampsia more accurately than either protein measured alone, with strong overall performance (Zhang et al., 2025). This is the same biomarker balance behind the newer FDA-cleared blood tests now entering clinical use. What this means for you: if you are being watched for preeclampsia, your care team may use one of these angiogenic blood tests to judge how likely the condition is to become severe, which can help them decide how closely to monitor you and when to act.
Researchers are also testing whether screening early in pregnancy, then treating high-risk people, can prevent the disease. A large 2024 trial across several regions in Asia offered first-trimester screening and gave low-dose aspirin to those found to be high risk. Among the women who actually took aspirin, the treatment was linked to a 41 percent reduction in preterm preeclampsia (Nguyen-Hoang et al., 2024). What this means for you: identifying risk early and starting aspirin before 16 weeks appears to make a real difference, which is why an early conversation with your provider about your risk is worthwhile.
Questions remain about the best way to use that aspirin. A 2025 nationwide study in Sweden compared women who took a higher dose of aspirin, 150 to 160 mg, with those who took 75 mg, examining both preeclampsia and bleeding (Kupka et al., 2025). Studies like this are helping refine the dose and timing that give the most protection with the least risk. What this means for you: the general advice to use low-dose aspirin when you are at high risk is well established, but the exact dose is best set by your own clinician, who can weigh your risk factors against any concern about bleeding.
Glossary of key terms
| Term | Definition |
|---|---|
| Preeclampsia | New high blood pressure after 20 weeks of pregnancy, plus protein in the urine or signs of organ involvement. |
| Eclampsia | Seizures that can occur as a severe progression of preeclampsia, a medical emergency. |
| HELLP syndrome | A severe form marked by hemolysis, elevated liver enzymes, and low platelets. |
| Proteinuria | Protein leaking into the urine, a sign that the kidneys are affected. |
| Placenta | The organ that supplies the baby with blood and oxygen and that drives preeclampsia. |
| sFlt-1/PlGF ratio | A blood test comparing two placental proteins to help predict severe preeclampsia. |
| Magnesium sulfate | An intravenous medicine used to prevent and treat the seizures of eclampsia. |
| Postpartum preeclampsia | Preeclampsia that develops after delivery, usually within the first week. |
Frequently asked questions
What are the warning signs of preeclampsia?
Preeclampsia is often silent, so many people have no symptoms and are diagnosed only through routine blood-pressure and urine checks. When warning signs do occur, the most important are a severe or persistent headache, vision changes such as blurring or flashing lights, pain in the upper right abdomen under the ribs, sudden swelling of the face and hands, rapid weight gain, and shortness of breath. Any of these in the second half of pregnancy should prompt a call to your obstetric provider right away.
When does preeclampsia usually start?
Preeclampsia most often develops after 20 weeks of pregnancy, and the majority of cases appear in the third trimester after about 27 weeks. It can begin earlier in some people, and a form called postpartum preeclampsia can start after the baby is born, usually within the first few days to a week of delivery. Because it can arrive without warning, regular prenatal visits through the whole pregnancy are the best way to catch it.
What causes preeclampsia?
Preeclampsia starts with the placenta, whose blood vessels develop abnormally and carry less blood than they should. The stressed placenta releases proteins that damage the lining of the mother’s blood vessels, driving up blood pressure and affecting the kidneys, liver, and other organs. This involves an imbalance between the proteins sFlt-1 and PlGF. Certain factors raise the risk, including a first pregnancy, a prior history of preeclampsia, chronic high blood pressure, diabetes, kidney disease, obesity, carrying multiples, and age over 35.
Can preeclampsia be cured, and how is it treated?
The only cure for preeclampsia is delivery of the baby and placenta, and timing that delivery means balancing the mother’s safety against the baby’s need to mature. Before delivery, treatment includes blood-pressure medicines that are safe in pregnancy, such as labetalol, nifedipine, and hydralazine, along with intravenous magnesium sulfate to prevent seizures in severe cases. If early delivery is likely, corticosteroids may be given to help the baby’s lungs mature. Close monitoring of both mother and baby continues throughout.
How can I lower my risk of preeclampsia?
If you are at high risk, U.S. guidelines recommend low-dose aspirin, usually 81 mg daily, started between 12 and 28 weeks of pregnancy and ideally before 16 weeks, which can meaningfully reduce the chance of developing preeclampsia. Calcium supplementation helps in people with low dietary calcium. Managing chronic conditions such as high blood pressure and diabetes, attending every prenatal visit, and maintaining a healthy weight all help. Talk with your provider early about whether aspirin is right for you.
Can you get preeclampsia after giving birth?
Yes. Postpartum preeclampsia develops after delivery, most often within the first few days to a week, though it can appear up to about six weeks later. The warning signs are the same as during pregnancy: severe headache, vision changes, upper abdominal pain, swelling, and shortness of breath. Because it can be easy to dismiss symptoms as normal recovery, anyone who notices these signs after giving birth should seek medical care promptly, as postpartum preeclampsia can be just as serious.
Sources
- American College of Obstetricians and Gynecologists — Preeclampsia and High Blood Pressure During Pregnancy — ACOG Frequently Asked Questions, 2023 — acog.org
- Mayo Clinic — Preeclampsia: Symptoms and Causes — Mayo Clinic Diseases and Conditions, 2024 — mayoclinic.org
- Cleveland Clinic — Preeclampsia — Cleveland Clinic Health Library, 2024 — my.clevelandclinic.org
- MedlinePlus, National Library of Medicine — Preeclampsia — MedlinePlus Medical Encyclopedia, reviewed 2024 — medlineplus.gov
- Zhang R, Li J, Chi Y, Sun L, et al. — Predictive performance of sFlt-1, PlGF and the sFlt-1/PlGF ratio for preeclampsia: A systematic review and meta-analysis — Journal of Gynecology Obstetrics and Human Reproduction, 2025 — doi.org/10.1016/j.jogoh.2025.102925
- Nguyen-Hoang L, Dinh LT, Tai AST, et al. — Implementation of First-Trimester Screening and Prevention of Preeclampsia: A Stepped Wedge Cluster-Randomized Trial in Asia — Circulation, 2024 — doi.org/10.1161/CIRCULATIONAHA.124.069907
- Kupka E, Hesselman S, Gunnarsdóttir J, Wikström AK, et al. — Prophylactic Aspirin Dose and Preeclampsia — JAMA Network Open, 2025 — doi.org/10.1001/jamanetworkopen.2024.57828
Further reading
- Learn how a marker of cell and tissue injury is measured by reading about what LDH shows on a blood test.
- Understand how proteinuria is quantified by reviewing how a 24-hour urine protein test is interpreted.
- Explore an autoimmune condition that can raise preeclampsia risk in this guide to lupus symptoms, causes, and treatment options.
- Review the companion liver enzyme to AST by reading what the ALT liver enzyme test measures.
- Build a fuller picture of your own numbers with this guide to reading reference ranges, flags, and trends in a lab report.
Understand your lab results with BloodSense
A preeclampsia diagnosis rests on more than a blood-pressure reading. It draws on a panel of blood and urine tests, from platelet counts and liver enzymes to creatinine, uric acid, and the sFlt-1/PlGF ratio, each one showing how the condition is affecting the body. Those results can be hard to make sense of on your own, especially when they mention reference ranges, flags, or unfamiliar markers.
BloodSense translates a full lab report into plain language, showing where each marker sits relative to its reference range and helping you understand what a normal, borderline, or abnormal result actually means for your health. Get your results interpreted in minutes
