Preeclampsia affects roughly 4 to 5 percent of pregnancies worldwide, making it one of the most common serious complications of pregnancy and a leading cause of maternal and infant illness globally. That single-digit percentage translates into tens of millions of cases each year, with the burden falling unevenly across regions, racial groups, and age brackets. The story behind these numbers is more complicated than a single prevalence figure suggests, and it has been shifting in ways that matter for anyone planning a pregnancy or caring for someone who is.
How Common Is Preeclampsia Around the World
A 2025 systematic review pooling data from 70 studies and over 2.4 million participants estimated the global prevalence of preeclampsia at about 4.4 percent, with eclampsia (the seizure-producing progression of the disease) at about 0.4 percent and HELLP syndrome at a similar rate.1PubMed Central. Global prevalence of preeclampsia, eclampsia, and HELLP syndrome: a systematic review and meta-analysis Those averages obscure enormous geographic variation. A scoping review covering 143 studies across 31 countries found that the African region reported the highest composite rates of hypertensive disorders in pregnancy, at over 22 percent, while the Eastern Mediterranean region reported the lowest preeclampsia prevalence at about 1.5 percent.2Frontiers in Cardiovascular Medicine. Global prevalence of hypertensive disorders of pregnancy: a scoping review and global perspective by country and region The Americas fell somewhere in the middle, with a preeclampsia prevalence around 5.4 percent, and Europe came in lower at roughly 2.5 percent.
The gap between high- and low-income settings is especially stark. The World Health Organization has estimated that preeclampsia’s incidence in developing countries is about seven times higher than in developed ones.3PubMed Central. Public Health Perspectives of Preeclampsia in Developing Countries: Implication for Health System Strengthening Part of this difference reflects access to prenatal care, which catches the condition earlier and manages blood pressure before it spirals. Part of it reflects different rates of underlying risk factors like chronic hypertension, obesity, and diabetes. And part of it is simply that eclampsia kills more women in places where emergency obstetric care is not available, meaning fewer women survive long enough to be counted in less severe categories.
Rates Have Been Climbing
Preeclampsia is not a static problem. Between 1990 and 2021, the global incidence of hypertensive disorders in pregnancy rose by about 15 percent, from roughly 31 million cases to 36 million.4Scientific Reports. Trends in global and regional incidence and prevalence of hypertensive disorders in pregnancy (1990–2021): an age-period-cohort analysis Some of that increase is explained by population growth and shifts in maternal age, but the age-standardized rate also climbed, suggesting something beyond demographics is at play.
In the United States, the picture has been especially concerning. A study analyzing U.S. birth data from 1987 to 2004 found that preeclampsia rates rose by 25 percent and gestational hypertension rates jumped by 184 percent over that period.5American Journal of Hypertension. Secular Trends in the Rates of Preeclampsia, Eclampsia, and Gestational Hypertension, United States, 1987–2004 A longer-term analysis spanning 1980 to 2010 found that women delivering in 2003 faced nearly seven times the risk of severe preeclampsia compared to women delivering in 1980.6PubMed. Pre-eclampsia rates in the United States, 1980-2010: age-period-cohort analysis Rising obesity and declining smoking rates (smoking, oddly, has a modest protective effect against preeclampsia) were associated with these trends but did not fully explain them.
A more recent study tracking nearly 300,000 pregnancies found the incidence of preeclampsia climbing from 8 to 11 percent over the study period, with twin pregnancies and pre-gestational diabetes steadily contributing more cases over time.7PubMed. Changes in trends over time for the specific contribution of different risk factors for pre-eclampsia Fertility treatments also played a role, though their contribution showed a mixed trend as assisted reproduction technology has evolved.
The Major Risk Factors
Preeclampsia has a long list of recognized risk factors, but a few stand out for their strength and consistency across studies. A case-control study in Peru identified prior preeclampsia history as the single strongest predictor, with an adjusted odds ratio of 5.4, meaning women who had preeclampsia before were roughly five times more likely to develop it again.8PubMed Central. Clinical, social, and occupational determinants of severe preeclampsia: a multifactorial case-control study on maternal health inequities in Peru That same study found chronic hypertension, obesity, being a first-time mother, insufficient prenatal visits, high physical workload, and psychosocial stress all independently increased the odds.
Diabetes is a particularly strong driver. Women with type 1 or type 2 diabetes before pregnancy are about four times more likely to develop preeclampsia than women without diabetes, and the condition ends up affecting somewhere between 7 and 20 percent of diabetic pregnancies depending on diabetes type and management.9Frontiers in Endocrinology. Prediction and prevention of preeclampsia in women with preexisting diabetes: the role of home blood pressure, physical activity, and aspirin
Twin pregnancies also carry elevated risk. In one study of over 4,400 twin pregnancies, about 7 percent developed preeclampsia overall, but the rate was substantially higher among IVF twins at nearly 14 percent, compared to about 8 percent for spontaneous twins.10PubMed. Preeclampsia acts differently in in vitro fertilization versus spontaneous twins Another study found that IVF roughly quadrupled the odds of early-onset preeclampsia in twin pregnancies specifically.11PubMed Central. Pregnancy outcomes and risk factors for preeclampsia in dichorionic twin pregnancies after in vitro fertilization: a five-year retrospective study For any twin pregnancy, nulliparity and chronic hypertension were the dominant clinical risk factors, while lower gestational weight gain appeared protective.12PubMed Central. Clinical risk factors for preeclampsia in twin pregnancies
Age Matters, but Not in a Simple Way
Maternal age affects preeclampsia risk at both extremes, and the pattern gets more interesting when you separate the disease from its complications. Women under 20 carry a higher overall risk for preeclampsia, eclampsia, and gestational hypertension.5American Journal of Hypertension. Secular Trends in the Rates of Preeclampsia, Eclampsia, and Gestational Hypertension, United States, 1987–2004 Teenagers aged 15 to 17 had nearly three times the risk of eclampsia compared to women aged 25 to 29, while women 45 and older faced more than double the risk of severe morbidity with transfusion.13American Journal of Obstetrics & Gynecology. Maternal age and preeclampsia outcomes
The type of complication shifts with age in revealing ways. When researchers compared preeclamptic women over 40 to younger preeclamptic women, the older group was more prone to acute kidney injury and new-onset postpartum preeclampsia, but actually had lower rates of HELLP syndrome and low platelets.14PubMed Central. The Association between Advanced Maternal Age and the Manifestations of Preeclampsia with Severe Features Older mothers who developed preeclampsia also had about three times the odds of poor maternal outcomes overall and worse perinatal outcomes, including higher rates of prematurity and growth restriction in their infants.15PubMed Central. Maternal Perinatal Outcomes Related to Advanced Maternal Age in Preeclampsia Pregnant Women
Racial and Ethnic Disparities
In the United States, Black women consistently face the highest risk of preeclampsia and its most dangerous consequences. In a large, diverse cohort, the age-adjusted prevalence of preeclampsia was 11 percent among non-Hispanic Black women, compared to about 9 percent among Hispanic women and 7 percent among non-Hispanic white women.16JAMA Network Open. Nativity-Related Disparities in Preeclampsia and Cardiovascular Disease Risk Among a Racially Diverse Cohort of US Women California data showed that non-Hispanic Black mothers had about 50 percent higher rates of gestational hypertension and preeclampsia and more than double the rate of chronic hypertension compared to white mothers, a gap that persisted throughout the study period.17PubMed Central. Trends and Racial and Ethnic Disparities in Maternal Cardiovascular Health in California
The crucial question is why. A growing body of evidence points away from biology and toward social determinants. One decomposition analysis estimated that social factors including education, dietary patterns, and sociodemographic conditions explained roughly 71 percent of the Black-white disparity in preeclampsia, with the mother’s education alone accounting for over half of the gap.18PubMed Central. Social Determinants of Health and Disparities in Pregnancy Outcomes Similarly, when cardiovascular risk factors like hypertension and obesity were accounted for, the statistical gap between Black and white women largely disappeared, suggesting that unequal access to care and the chronic stress of structural disadvantage drive much of the disparity rather than inherent biological differences.16JAMA Network Open. Nativity-Related Disparities in Preeclampsia and Cardiovascular Disease Risk Among a Racially Diverse Cohort of US Women Higher rates of the contributing comorbidities themselves, particularly hypertension and obesity, are largely associated with lower access to care in Black communities.19PubMed. Understanding Health Disparities in Preeclampsia: A Literature Review
Complications During Pregnancy
Most women with preeclampsia recover fully after delivery, which remains the definitive treatment. But a meaningful minority develop serious complications. Across studies, about 6 percent of women with preeclampsia develop at least one major systemic complication, including placental abruption (roughly 3 percent) and eclamptic seizures (under 2 percent).20PubMed. The incidence of severe complications of preeclampsia Blood-related problems, especially dropping platelet counts, are the most common category of serious complication. About 10 percent of women with preeclampsia experience postpartum hemorrhage.21PubMed Central. Incidence, characteristics, maternal complications, and perinatal outcomes associated with preeclampsia with severe features and HELLP syndrome
For the baby, the main risks are preterm birth and restricted growth. Preeclampsia, fetal growth restriction, and preterm birth share a common upstream problem: the placenta is not working properly.22PubMed. Placental Dysfunction as a Common Pathway Linking Preeclampsia, Fetal Growth Restriction, and Preterm Birth: Current Evidence and Future Directions Interestingly, when researchers looked at very preterm infants at two years of age, preeclampsia on its own was not associated with lower developmental scores. What did predict poorer outcomes was fetal growth restriction, regardless of whether preeclampsia was present.23JAMA Network Open. Preeclampsia, Fetal Growth Restriction, and 24-Month Neurodevelopment in Very Preterm Infants That distinction matters: preeclampsia increases the odds of growth restriction, but the developmental harm appears to come from the growth restriction itself, not the maternal blood pressure problem.
Long-Term Cardiovascular Risk for Mothers
One of the most important findings about preeclampsia in recent decades is that the cardiovascular risk does not end with delivery. A systematic review and meta-analysis found that women with a history of preeclampsia face roughly double the risk of coronary heart disease, stroke, and cardiovascular death later in life, and about a fourfold increase in the risk of heart failure.24PubMed. Preeclampsia and Future Cardiovascular Health: A Systematic Review and Meta-Analysis A more recent meta-analysis confirmed elevated risks across the board: about double the odds of coronary artery disease, roughly 2.5 times the risk of heart failure, and about 1.75 times the risk of stroke, even after adjusting for traditional cardiovascular risk factors.25European Heart Journal – Quality of Care and Clinical Outcomes. Update on long-term cardiovascular risk after pre-eclampsia: a systematic review and meta-analysis
The connection appears to involve shared mechanisms: the endothelial damage and inflammation that drive preeclampsia may leave lasting changes in the blood vessels, and women with severe or recurrent preeclampsia often develop chronic hypertension within a decade of delivery.26PubMed Central. Long-Term Cardiovascular Risk and Maternal History of Pre-Eclampsia These structural changes, including thickening of the heart muscle and impaired relaxation of the ventricles, can set the stage for heart failure years or decades later. This is why major cardiology organizations now recognize a history of preeclampsia as a cardiovascular risk factor in its own right.
Long-Term Outcomes for Children
The effects on offspring extend beyond the neonatal period. A large population-based study found that children born at full term after preeclampsia-exposed pregnancies had higher hospitalization rates for endocrine and metabolic diseases and diseases of the blood and blood-forming organs, with rates about 50 to 60 percent higher than unexposed children.27American Journal of Obstetrics and Gynecology. Health of children born to mothers who had preeclampsia: a population-based cohort study A Finnish study looking at neurodevelopmental outcomes found that children exposed to preeclampsia at term had modestly elevated risks of ADHD, autism spectrum disorder, epilepsy, and intellectual disability.28JAMA Psychiatry. Association of Preeclampsia in Term Births With Neurodevelopmental Disorders in Offspring These increased risks were statistically significant but relatively modest in absolute terms. The working theory is that the preeclamptic environment may induce epigenetic changes during fetal development that influence health trajectories into childhood and beyond.29PubMed Central. Short- and Long-Term Outcomes of Preeclampsia in Offspring: Review of the Literature
How Diagnostic Criteria Change the Numbers
Some of the apparent rise in preeclampsia rates is real, but some of it is an artifact of changing definitions. Major obstetric organizations have revised their diagnostic criteria multiple times, and each revision tends to capture more women. The updated guidelines from the International Society for the Study of Hypertension in Pregnancy and the American College of Obstetricians and Gynecologists expanded the definition beyond the traditional requirement of proteinuria (protein in the urine), allowing diagnosis when elevated blood pressure is accompanied by other organ damage like liver dysfunction, low platelets, or kidney impairment.
One study comparing the newer criteria to older ones found that the ISSHP 2018 criteria identified about 15 percent more women with preeclampsia than the older 2001 definition, while the ACOG 2013 criteria identified about 6 percent more.30American Journal of Obstetrics & Gynecology. Challenging the definition of hypertension in pregnancy: a retrospective cohort study A separate study found a similar pattern, with prevalence jumping from about 6 percent to 8 percent depending on which criteria were applied.31Pregnancy Hypertension. Evaluation of the clinical impact of the revised ISSHP and ACOG definitions on preeclampsia The women captured only by the newer definitions tend to have milder disease: lower rates of severe hypertension, fewer preterm deliveries, and fewer neonatal intensive care admissions.32PubMed. Comparing severity of different subtypes of preeclampsia using different diagnostic criteria – a retrospective cohort study This matters because global prevalence estimates depend heavily on which definition a study uses, and comparing rates across countries or decades requires knowing whether the diagnostic goalposts moved.
Aspirin for Prevention
Low-dose aspirin is the only intervention with strong trial evidence for reducing preeclampsia risk in high-risk women. The landmark ASPRE trial found that aspirin taken from the first trimester cut the rate of preterm preeclampsia from about 4.3 percent in the placebo group to 1.6 percent in the aspirin group, a reduction of more than 60 percent.33PubMed. Aspirin versus Placebo in Pregnancies at High Risk for Preterm Preeclampsia A meta-analysis of randomized trials estimated an overall 28 percent reduction in preeclampsia risk with aspirin in high-risk women.34Frontiers in Cardiovascular Medicine. Aspirin for the prevention of preeclampsia: A systematic review and meta-analysis of randomized controlled studies
Dose matters. A meta-analysis comparing lower-dose aspirin (75 to 81 mg, the standard dose in many countries) to higher-dose aspirin (150 to 162 mg) found the higher dose cut preterm preeclampsia risk by about two-thirds compared to the lower dose.35American Journal of Obstetrics & Gynecology MFM. Comparing aspirin 75 to 81 mg vs 150 to 162 mg for prevention of preterm preeclampsia: systematic review and meta-analysis Most current guidelines recommend starting aspirin before 16 weeks of pregnancy in women with recognized risk factors. Timing is critical: the benefit shrinks if aspirin is started later in pregnancy, likely because it works by improving the placental blood vessel development that happens early on.
The Economic Cost
Preeclampsia is expensive, and the costs fall disproportionately on infant care. A U.S. study found that the combined maternal and infant medical costs in pregnancies complicated by preeclampsia averaged about $42,000, compared to roughly $13,000 for uncomplicated pregnancies. The infant costs drove most of the difference, averaging about $29,000 in the preeclampsia group versus about $3,700 in uncomplicated births.36PubMed Central. Maternal and Infant Health Care Costs Related to Preeclampsia The cost per infant depends steeply on gestational age at delivery, ranging from roughly $150,000 for an infant born at 26 weeks to about $1,300 at 36 weeks.37American Journal of Obstetrics and Gynecology. The rising burden of preeclampsia in the United States impacts both maternal and child health The same analysis estimated that preeclampsia added about $2.18 billion annually in excess costs to the U.S. healthcare system, split roughly evenly between maternal and infant care.
Postpartum Preeclampsia Is Increasingly Recognized
Preeclampsia does not always appear before delivery. New-onset postpartum preeclampsia, in which blood pressure spikes and symptoms develop days or weeks after birth, is a growing clinical concern. Among women with hypertensive disorders during pregnancy, about 4.4 percent were readmitted to the hospital postpartum, with the typical readmission happening around day five after delivery.38PubMed. Factors associated with postpartum readmission for hypertensive disorders of pregnancy At the population level, the rate of hospital readmissions for postpartum hypertension in the U.S. more than doubled between 2010 and 2019, rising from about 0.36 percent to 0.8 percent of all delivery hospitalizations.39PubMed Central. Temporal changes in hospital readmissions for postpartum hypertension in the US, 2010 to 2019; a serial cross-sectional analysis This doubling likely reflects a mix of genuine increase and better recognition, as awareness campaigns have encouraged new mothers to seek care for symptoms like severe headaches and vision changes after going home.
Heat Exposure and Environmental Links
An emerging area of research connects environmental temperature to preeclampsia risk. A study in Guangzhou, China, found that exposure to extreme or moderate high temperatures during early pregnancy (specifically during weeks 1 through 8) was associated with roughly 22 to 24 percent higher odds of preeclampsia, and the effect was stronger in women with higher pre-pregnancy body mass.40PubMed. Association of air temperature exposure during pregnancy with risk of preeclampsia in Guangzhou, China A large systematic review confirmed the pattern, finding that the majority of studies linking heat exposure to hypertensive disorders of pregnancy showed a positive association, with a clear dose-response effect seen in a Chinese cohort of over two million pregnancies.41Nature Medicine. A systematic review and meta-analysis of heat exposure impacts on maternal, fetal and neonatal health Given that global temperatures continue to rise, this connection between heat and pregnancy complications is likely to become increasingly relevant in the coming decades, particularly in tropical and subtropical regions where preeclampsia rates are already high.
Why Humans Are Uniquely Vulnerable
Preeclampsia is essentially unique to humans, and researchers think this is not a coincidence. The condition appears tied to two features that distinguish human reproduction from that of other mammals: the unusually deep invasion of placental tissue into the uterine wall and the enormous metabolic demands of the developing human brain. Both evolved together over millions of years, and both create a pregnancy that places extraordinary demands on the maternal cardiovascular system.42PubMed. An anthropological perspective on the evolutionary context of preeclampsia in humans Evolutionary analyses suggest that a tendency toward the condition emerged at the origin of the great apes and became more severe during the evolution of modern humans, as brain size increased and the birth process became more physically constrained.43Pregnancy Hypertension: An International Journal of Women’s Cardiovascular Health. Evolutionary origins of preeclampsia In this view, preeclampsia is not so much a disease that should have been selected away as a side effect of the evolutionary bargain that gave humans their large, costly brains. Medical intervention has turned what was once a frequently fatal complication into a manageable, though still dangerous, one.