Overview
Preeclampsia is a pregnancy complication marked by high blood pressure and signs of organ stress, most often detected after 20 weeks of gestation. One of its hallmark features is protein in the urine, known as proteinuria or urinary protein excretion (UPE). Although preeclampsia usually improves after delivery, it is increasingly recognized as a warning sign for a woman’s future health.
This population-based cohort study from Denmark examined whether the amount of protein excreted in the urine during preeclampsia is linked to long-term risks of maternal hypertension, chronic kidney disease (CKD), and cardiovascular disease (CVD). The findings suggest that preeclampsia is associated with higher long-term risks of these conditions, and that higher proteinuria levels are especially predictive of later kidney disease and, to a lesser extent, later hypertension.
Why this study matters
Proteinuria has long been used as a diagnostic clue in preeclampsia, but its prognostic meaning has been less certain. Clinicians have often focused on blood pressure, delivery timing, and short-term maternal and fetal safety. This study adds an important longer view: the degree of protein loss in urine during pregnancy may reflect the extent of vascular and kidney injury, which can persist beyond childbirth.
That matters because women with a history of preeclampsia already face higher lifetime risks of chronic hypertension, kidney dysfunction, stroke, coronary disease, and other cardiovascular complications. If urine protein level helps identify those at especially high risk, follow-up care can be better targeted after pregnancy.
Study design and population
The investigators used nationwide, routinely collected health data from Denmark over a 20-year period, from 1998 to 2018, with follow-up through 2021. This type of cohort study is powerful because it includes a very large number of pregnancies and reflects real-world clinical practice rather than a single hospital or specialty center.
The study included all pregnancies lasting at least 20 weeks among women aged 15 years or older. In total, 286,078 pregnant women were analyzed. Among them, 9,538 women, or 3.3%, developed preeclampsia.
The researchers then compared long-term outcomes between women with and without preeclampsia. They also divided preeclampsia into two severity groups based on urine protein or albumin cutoffs: no/mild urinary protein excretion and moderate/severe urinary protein excretion.
What outcomes were measured
The main outcomes were later diagnosis of hypertension, chronic kidney disease, and cardiovascular disease. The team estimated cumulative incidence, which is the proportion of women who developed each condition over time. They also calculated adjusted risk differences and risk ratios to account for important confounders such as age, smoking, obesity, region of residence, and calendar year.
In practical terms, this means the results were not simply due to one group being older or having more risk factors than another. The analysis aimed to isolate the contribution of preeclampsia itself, and the contribution of proteinuria severity within preeclampsia.
Main findings
The study confirmed that preeclampsia is associated with increased long-term maternal risk of hypertension, CKD, and CVD. The 10-year risk estimates were especially informative.
Among women with preeclampsia and no/mild urinary protein excretion, the 10-year risk was 11.9% for hypertension, 1.2% for CKD, and 1.1% for CVD.
Among women with preeclampsia and moderate/severe urinary protein excretion, the 10-year risk rose to 16.0% for hypertension, 5.1% for CKD, and 1.2% for CVD.
These numbers show a clear pattern: more protein in the urine during preeclampsia was associated with a higher later risk of chronic kidney disease and, to a more moderate degree, hypertension. For cardiovascular disease, the pattern was less clearly tied to proteinuria level, although preeclampsia itself still signaled increased long-term risk.
Interpretation of the results
The most notable signal in this study is the relationship between greater urinary protein excretion and later CKD. This is biologically plausible. Preeclampsia affects the endothelium, kidneys, and placental circulation, and severe proteinuria may indicate more significant kidney injury or more intense systemic disease during pregnancy.
Hypertension also showed a meaningful association with preeclampsia, regardless of proteinuria severity. This suggests that preeclampsia is not only a pregnancy-limited disorder but may also reveal an underlying tendency toward future vascular disease.
Cardiovascular disease risk was elevated overall after preeclampsia, but in this study it did not differ much between the proteinuria severity groups. That may mean that mechanisms other than proteinuria, such as shared metabolic risk factors, endothelial dysfunction, or inflammatory pathways, play a larger role in later CVD than urine protein level alone.
Clinical implications
These findings support closer long-term follow-up for women who have had preeclampsia, especially those with moderate or severe proteinuria. Follow-up should not end at delivery or the postpartum visit. Instead, postpartum care should include blood pressure monitoring, kidney function assessment, and cardiovascular risk reduction counseling.
Useful follow-up measures may include checking blood pressure regularly, measuring serum creatinine and estimated glomerular filtration rate, assessing urine protein or albumin if clinically indicated, and addressing modifiable risk factors such as obesity, smoking, inactivity, and poor diet. For some women, primary care or nephrology referral may be appropriate.
Importantly, this study does not mean that every woman with preeclampsia will develop CKD or cardiovascular disease. The absolute risks remain modest for many individuals. However, the relative increase is clinically meaningful, especially because preeclampsia often occurs in women who are otherwise young and may otherwise be overlooked for long-term prevention.
How proteinuria is used in preeclampsia
In everyday obstetric care, proteinuria helps clinicians confirm the diagnosis of preeclampsia when it appears alongside new-onset hypertension. Protein loss in the urine can be measured by a protein-to-creatinine ratio, albumin-to-creatinine ratio, or timed urine collection, depending on local practice.
This study used established cutoffs to distinguish no/mild from moderate/severe levels. While exact thresholds may vary by guideline and laboratory method, the general principle is that more proteinuria reflects greater disease burden. The study suggests that this burden has value beyond diagnosis: it may help estimate long-term maternal risk.
Strengths and limitations
A major strength of the study is its large, nationwide design with long follow-up. This makes the results more generalizable and reduces the chance that the findings are due to a small sample or one particular clinic. Another strength is the use of routinely collected health data, which allowed the investigators to capture real-world pregnancies over two decades.
However, like all observational studies, this one cannot prove that proteinuria causes later kidney or cardiovascular disease. It shows association, not direct causation. Also, some clinical details may not have been available, such as exact antihypertensive treatment, detailed laboratory trends, or lifestyle changes after pregnancy. Residual confounding is always possible in population studies.
Another important point is that preeclampsia itself may be heterogeneous. Some cases are driven more by placental disease, others by maternal cardiovascular susceptibility, and others by underlying kidney vulnerability. Proteinuria may be one marker of this complexity rather than the sole driver of later risk.
What patients and clinicians should take away
For patients, the key message is that preeclampsia is not only a pregnancy complication but also a potential early warning sign for future health. If you had preeclampsia, especially with significant proteinuria, it is wise to remain engaged in follow-up care and to mention this history to your primary care clinician and any future obstetric providers.
For clinicians, the study supports viewing preeclampsia as a cardiovascular and renal risk marker. Women with higher proteinuria during preeclampsia may deserve more proactive postpartum surveillance and earlier preventive care. This is especially important because many of these women are young, and early intervention may reduce long-term disease burden.
Bottom line
In this large Danish cohort, preeclampsia was linked to higher long-term risks of hypertension, chronic kidney disease, and cardiovascular disease. Higher urinary protein excretion during preeclampsia was particularly associated with greater later risk of hypertension and CKD. The results reinforce the idea that pregnancy complications can reveal future maternal health risks and should prompt ongoing medical follow-up after delivery.
Reference: Vestergaard AHS, Svane HML, Jensen SK, Heide-Jørgensen U, Conte C, Romagnani P, Christiansen CF. Proteinuria in Preeclampsia and Long-Term Risk of Maternal Kidney and Cardiovascular Disease: A Population-Based Cohort Study. BJOG. 2026.
