Preeclampsia is a hypertensive disorder unique to pregnancy, characterized by new-onset hypertension and proteinuria or end-organ dysfunction after 20 weeks of gestation (1). It remains one of the leading causes of maternal and perinatal morbidity and mortality, particularly in low- and middle-income countries (2). Despite advancements in obstetric care, timely identification of women at risk remains a clinical challenge.

The pathophysiology of preeclampsia is complex and involves abnormal placentation, endothelial dysfunction, and an imbalance between angiogenic and anti-angiogenic factors (3). Biomarkers reflecting these changes, such as Placental Growth Factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), and Pregnancy-Associated Plasma Protein-A (PAPP-A), have been investigated for their role in early prediction (4,5). Additionally, Doppler ultrasound evaluation of the uterine artery pulsatility index (UtA-PI) offers insight into impaired uteroplacental perfusion, which is a hallmark of the disease (6).

Several studies have reported the utility of individual biomarkers, but results vary due to differences in population, timing, and diagnostic criteria (7). Moreover, integrated models combining biochemical and biophysical markers are emerging as promising tools for first-trimester screening (8). However, multi-center data on their comparative effectiveness and combined predictive accuracy remain limited.

This study aims to evaluate and compare the predictive value of select maternal biomarkers—PlGF, sFlt-1, PAPP-A, and UtA-PI—individually and in combination, for early identification of preeclampsia in a diverse cohort across multiple tertiary care centers.

Study Design and Setting

This prospective cohort study was conducted over a period of 18 months, from January 2023 to June 2024, across five tertiary care hospitals located in different regions of India. Written informed consent was obtained from all participants prior to enrollment.

Study Population

A total of 600 pregnant women with singleton pregnancies were enrolled between 11 and 14 weeks of gestation during their first antenatal visit. Inclusion criteria included maternal age between 18 and 40 years, confirmed gestational age based on last menstrual period and ultrasound, and willingness to participate in follow-up until delivery. Women with chronic hypertension, renal disease, diabetes mellitus, autoimmune disorders, or multiple pregnancies were excluded.

Data Collection

Baseline demographic and obstetric data were recorded. At the time of recruitment, maternal blood samples were collected for biomarker analysis. Serum levels of Placental Growth Factor (PlGF), soluble fms-like tyrosine kinase-1 (sFlt-1), and Pregnancy-Associated Plasma Protein-A (PAPP-A) were measured using standardized enzyme-linked immunosorbent assay (ELISA) kits. All samples were processed within two hours of collection and stored at -80°C until analysis.

Ultrasound Evaluation

All participants underwent transabdominal Doppler ultrasound to measure the uterine artery pulsatility index (UtA-PI) during the same gestational window. Measurements were taken bilaterally, and the mean value was used for analysis.

Follow-Up and Outcome Assessment

Participants were followed through routine antenatal care until delivery. The primary outcome was the development of preeclampsia, defined according to the criteria of the American College of Obstetricians and Gynecologists: new-onset hypertension (≥140/90 mmHg) and proteinuria (≥300 mg/24 h) or signs of end-organ damage after 20 weeks of gestation.

Statistical Analysis

Data were analyzed using SPSS version 25.0 (IBM Corp., Armonk, NY). Continuous variables were expressed as mean ± standard deviation and compared using the independent t-test or Mann-Whitney U test, as appropriate. Categorical variables were analyzed using chi-square or Fisher’s exact test. Receiver Operating Characteristic (ROC) curves were constructed to assess the predictive value of individual and combined biomarkers. A p-value <0.05 was considered statistically significant.

Out of the 600 enrolled participants, 580 completed the study. A total of 92 women (15.9%) developed preeclampsia, while the remaining 488 participants had normotensive pregnancies. The baseline characteristics of both groups were comparable in terms of maternal age, gestational age at recruitment, and BMI (Table 1).

Table 1: Baseline Demographic and Clinical Characteristics of Study Participants

There were statistically significant differences in biomarker levels between the two groups. Women who later developed preeclampsia showed higher mean sFlt-1 levels and lower PlGF and PAPP-A levels compared to normotensive controls (Table 2). The mean sFlt-1/PlGF ratio was markedly elevated in the preeclampsia group.

Table 2: Comparison of Biomarker Levels Between Groups

ROC curve analysis revealed that the sFlt-1/PlGF ratio had the highest predictive accuracy (AUC = 0.89), followed by UtA-PI (AUC = 0.83) and PAPP-A (AUC = 0.76). When biomarkers were combined in a multivariate model, the predictive accuracy improved significantly (AUC = 0.91), as shown in Table 3.

Table 3: Predictive Performance of Biomarkers for Early Detection of Preeclampsia

The integrated biomarker panel showed improved discriminative ability compared to individual markers alone (Table 3), indicating its potential value in first-trimester screening for preeclampsia.

DISCUSSION

This multi-center cohort study assessed the predictive value of select maternal biomarkers—PlGF, sFlt-1, PAPP-A, and UtA-PI—for early detection of preeclampsia. The findings indicate that individual biomarkers such as PlGF and sFlt-1 provide substantial predictive accuracy, and their combined assessment along with uterine artery Doppler indices significantly enhances diagnostic performance.

Consistent with previous studies, women who later developed preeclampsia exhibited reduced serum PlGF levels and elevated sFlt-1 concentrations (1–3). The inverse relationship between PlGF and sFlt-1 reflects the disrupted angiogenic balance central to preeclampsia pathogenesis (4). The significantly elevated sFlt-1/PlGF ratio in our cohort mirrors findings from the PROGNOSIS study, which established its clinical utility in predicting short-term development of preeclampsia (5).

PAPP-A, a marker of placental function, was also found to be lower in the preeclampsia group, supporting earlier reports suggesting that impaired trophoblast invasion may be reflected in its early gestational levels (6,7). However, as an isolated marker, its predictive power was modest, highlighting the need for its use in combination with other parameters.

Uterine artery Doppler assessment remains a valuable non-invasive technique for evaluating placental perfusion. In our study, elevated UtA-PI in the first trimester was significantly associated with later development of preeclampsia, aligning with findings from the ASPRE trial (8,9). The role of biophysical markers such as UtA-PI in improving the sensitivity of biochemical screening tools has been increasingly emphasized (10).

The combination of sFlt-1, PlGF, PAPP-A, and UtA-PI achieved an AUC of 0.91 in our analysis, indicating excellent predictive performance. This supports recent meta-analyses advocating for multi-marker models to enhance first-trimester risk stratification (11,12). Early identification allows for the potential initiation of preventive interventions, such as low-dose aspirin, which has been shown to reduce the incidence of preterm preeclampsia when started before 16 weeks of gestation (13).

One strength of this study is its multi-center design, which increases generalizability and accounts for regional diversity. The large sample size and prospective data collection also add robustness to the findings. Nonetheless, some limitations should be acknowledged. The variability in laboratory infrastructure across centers may have influenced biomarker measurements, although efforts were made to standardize assay procedures. Furthermore, long-term maternal and neonatal outcomes were not evaluated, which could provide deeper insight into the clinical utility of early prediction.

Future studies should consider longitudinal biomarker assessment and explore the integration of novel markers such as microRNAs and exosomal proteins (14,15). Additionally, the cost-effectiveness and feasibility of implementing multi-marker screening in routine antenatal care, especially in low-resource settings, warrant further investigation.

In conclusion, this study demonstrates that a combined biomarker approach using PlGF, sFlt-1, PAPP-A, and uterine artery Doppler significantly improves early prediction of preeclampsia. Implementation of such models into first-trimester screening protocols could pave the way for improved maternal and fetal outcomes through timely preventive care.

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