Preeclampsia (PE) is a major obstetric complication with severe short- and long-term consequences for both mother and fetus. Early detection is critical to mitigate PE-related morbidity and mortality. Effective screening tools are needed to identify women at risk, enabling timely preventive and therapeutic interventions.

Current screening methods primarily target placental biomarkers like sFLT1 and PlGF, which are limited to short-term predictions near symptom onset. Existing first-trimester assessments that incorporate maternal factors and Doppler metrics remain constrained by low sensitivity (<41%) in compliance with NICE and ACOG guidelines.

Recent advancements in cell free RNA (cf-RNA) analysis have revealed potential in first-trimester PE prediction. Findings from the PREMOM study (NCT04990141) established a molecular profile for early-onset preeclampsia (EOPE) and late-onset preeclampsia (LOPE) through cfRNA analysis, culminating in the development of the MaiRa Preeclampsia Test (Maternal Advanced and Innovative Preeclampsia Risk Assessment), which demonstrated high predictive performance for first- and second-trimester screening.

The current study hypothesizes that the MaiRa Preeclampsia Test is generalizable, maintaining its predictive accuracy in an independent cohort.

This multicentre, prospective observational study aims to validate the MaiRa Preeclampsia Test, a molecular screening tool for predicting early-onset preeclampsia (EOPE) and late-onset preeclampsia (LOPE) in the first and second trimesters of pregnancy. The study will evaluate its diagnostic accuracy, including sensitivity, specificity, predictive values, and area under the curve (AUC).

Study Design:

Duration: 40 months

• Recruitment and Sample Collection: 28 months
• Sample Analysis: 32 months
• Follow-Up: 8 months
• Statistical Analysis and Publication: 6 months Participants: 7,473 pregnant women from 12 tertiary hospitals in Spain.

Visits:

• Visit 1 (T1): 9-14 weeks' gestation (first blood sample)
• Visit 2 (T2): 15-26 weeks' gestation (second blood sample)
• Visit 3 (T3): ≥27 weeks' gestation (third blood sample)

Blood samples will be analyzed using the MaiRa Preeclampsia Test, with results correlated against obstetric outcomes as the gold standard. Data will be documented in an electronic Case Report Form (eCRF). Quality assurance will be maintained via continuous data monitoring and verification.

Inclusion Criteria:

• Signed informed consent approved by the Ethics Committee.
• Women ≥18 years of age at consent.
• Single gestation pregnancies with first sample collection (T1) possible between 9 and 14 weeks' gestation.

Exclusion Criteria:

• Active neoplasm.
• History of organ or bone marrow transplantation.
• Maternal transfusion within 8 weeks before sample collection.
• Evidence of early pregnancy loss at consent.
• Severe, uncontrolled infections.
• Other investigator-assessed risks that could compromise participation or data quality.

Pregnant women

Pregnant patients aged 18 years or older, recruited between 9 and 14 weeks' gestation during routine obstetrical follow-ups at referral hospitals.