Optimizing the Use of Aspirin for the Prevention of Preeclampsia (Optim-PRE)

June 18, 2026 updated by: Hospital Universitari Vall d'Hebron Research Institute

Pregnant women at higher risk for preeclampsia (PE) are currently recommended to take low-dose aspirin (acetylsalicylic acid, ASA) daily from the first trimester until 36 weeks of gestation. High-risk women are identified through a multiparametric first-trimester screening that combines maternal history, blood pressure, uterine artery blood flow, and placental growth factor (PlGF). Although this screening effectively identifies women at risk, the majority of those classified as high risk will not develop PE. As a result, a large proportion of pregnant women receive prolonged aspirin treatment without benefit, while remaining exposed to its potential side effects, including increased bleeding risk.

Aspirin prevents PE primarily by improving placental development during the first half of pregnancy. Whether continuing ASA beyond 24-28 weeks provides additional protection remains unclear. A previous randomized trial demonstrated that stopping ASA at 24-28 weeks was non-inferior to continuing until 36 weeks in a predominantly European population. However, whether this finding applies to more diverse populations, including women of African origin who carry a substantially higher baseline risk of PE, has not been established.

This is a multicenter, randomized, open-label, parallel-group, phase III non-inferiority trial conducted across sites in Europe and Africa. A total of 15,160 pregnant women at high risk for PE from first-trimester screening, currently under ASA treatment, will be randomized in a 1:1 ratio before 28 weeks of gestation to either discontinue ASA at 24-28 weeks or continue ASA until 36 weeks of gestation.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Detailed Description

The primary objective of the study is to demonstrate that in pregnant women at high risk for preeclampsia from first-trimester multiparametric screening, the incidence of preterm PE after discontinuation of ASA at 24-28 weeks of gestation is non-inferior to that of the control group, who continue ASA until 36 weeks.

Study Type

Interventional

Enrollment (Estimated)

15160

Phase

  • Phase 3

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Locations

  • Austria
  • Bulgaria
  • Ghana
      • Ofinso, Ghana
        • Saint Patrick Hospital
        • Contact:
      • Techiman, Ghana
  • Senegal
      • Dakar, Senegal
        • Hopital Phillipe Senghor
        • Contact:
      • Saint-Louis, Senegal
        • Centre Hospitalier Régional de Saint-Louis
        • Contact:
  • Spain
      • A Coruña, Spain
      • Alicante, Spain
      • Barcelona, Spain
      • Barcelona, Spain, 08035
      • Barcelona, Spain
        • Hospital De La Santa Creu I Sant Pau
        • Contact:
        • Contact:
          • Phone Number: +34935537048
      • Burgos, Spain
      • Cadiz, Spain
      • Granada, Spain
        • Hospital Universitario Virgen de las Nieve
        • Contact:
      • Jerez de la Frontera, Spain
        • Hospital Universitario de Jerez
        • Contact:
      • Las Palmas de Gran Canaria, Spain
      • Leganés, Spain
      • León, Spain
      • Lleida, Spain
      • Madrid, Spain
        • Fundacion Jimenez Diaz
        • Contact:
      • Murcia, Spain
      • Móstoles, Spain
      • Pamplona, Spain
        • Clínica Universidad de Navarra
        • Contact:
      • San Cristóbal de La Laguna, Spain
        • Hospital Universitario de Canarias
        • Contact:
        • Contact:
      • Santa Cruz de Tenerife, Spain
      • Terrassa, Spain
        • Consorci Sanitari de Terrassa
        • Contact:
      • Terrassa, Spain
        • Hospital Universitari Mutua Terrassa
        • Contact:
      • Torrejón de Ardoz, Spain
        • Hospital Universitario de Torrejon
        • Contact:
    • Andalusia
    • BARCELONA
      • Barcelona, BARCELONA, Spain, 08024
        • Hospital Universitari Dexeus
        • Contact:
    • Girona
      • Girona, Girona, Spain, 17007
        • Hospital Dr.Josep Trueta
        • Contact:
          • Roser Masó
          • Phone Number: 2235 972940200
    • Tarragona
    • Vizcaya
  • The Gambia
      • Banjul, The Gambia
        • Bundung Maternal and Child Health Hospital
        • Contact:
      • Brikama, The Gambia
        • Brikama District Hospital
        • Contact:
  • United Kingdom
      • London, United Kingdom
      • London, United Kingdom

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Age 18 years or older at time of enrollment.
  • Singleton pregnancy.
  • Ability to read and understand the informed consent form.
  • Having undergone first-trimester preeclampsia screening between 11+0 and 13+6 weeks of gestation using a validated multiparametric algorithm (FMF algorithm at a risk cutoff of 1:100, or Gaussian algorithm at a cutoff of 1:170) and being classified as high risk for preterm preeclampsia.
  • Currently taking aspirin 150 mg/day initiated after first-trimester high-risk classification, in accordance with standard clinical practice.
  • Voluntary signing of the informed consent form and willingness to comply with the study requirements, including acceptance of the assigned aspirin treatment duration, additional blood tests, and additional ultrasound assessments.

Exclusion Criteria:

  • Early pregnancy loss, intrauterine fetal death, or fetus with major structural malformations diagnosed at the time of enrollment.
  • Fetus affected by a known genetic or chromosomal disease.
  • Contraindication, allergy, or intolerance to aspirin (acetylsalicylic acid).
  • Any medical condition that makes aspirin discontinuation unsafe or impossible (e.g., antiphospholipid syndrome, mechanical heart valve, or other conditions requiring indefinite antiplatelet or anticoagulant therapy).

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Prevention
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: ASA withdrawn group
ASA is discontinued at 24-28 weeks of gestation
Drug: Discontinuation of Acetylsalicilic acid 150 mg/day at 24-28 weeks of gestation
Intervention group will discontinuate of Acetyl Salicylic acid at 24-28 weeks of gestation while Control Group will continue Acetyl Salicylic acid 150 mg/day until 36 weeks of gestation.
No Intervention: Continue ASA Group
ASA is continued until 36 weeks of gestation

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Rate of preterm preeclampsia in both arms of the study (ASA vs no ASA).
Time Frame: From 20 weeks of gestation onwards
Rate of pre-eclampsia <37 weeks in pregnant women at high-risk for early-onset PE from the first-trimester screening in both arms of the study (ASA vs no ASA).
From 20 weeks of gestation onwards

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Hospital Universitari Vall d'Hebron Research Institute

Collaborators

Fetal Medicine Foundation

Investigators

  • Principal Investigator: Manel Mendoza Cobaleda, Professor, Hospital Universitari Vall Hebron - Vall Hebrón Institut de Recerca
  • Principal Investigator: Kypros Nicolaides, Professor, Fetal Medicine Foundation

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

July 1, 2026

Primary Completion (Estimated)

May 1, 2028

Study Completion (Estimated)

May 1, 2028

Study Registration Dates

First Submitted

June 18, 2026

First Submitted That Met QC Criteria

June 18, 2026

First Posted (Actual)

June 24, 2026

Study Record Updates

Last Update Posted (Actual)

June 24, 2026

Last Update Submitted That Met QC Criteria

June 18, 2026

Last Verified

June 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • Optim-PRE26
  • INV-093057 (Other Grant/Funding Number: Bill And Melinda Gates Foundation)
  • INV-108812 (Other Grant/Funding Number: Bill And Melinda Gates Foundation)
  • PI25/00497 (Other Grant/Funding Number: Instituto de Salud Carlos III)
  • 2025-524646-94-00 (Ctis)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

YES

IPD Plan Description

Upon publication, anonymized data will be deposited in the VHIR's institutional open research data repository.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

product manufactured in and exported from the U.S.

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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