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Acetylsalicylic Acid for Preventing Preeclampsia in Pregnant Women

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What is this study about?

This clinical trial is studying preeclampsia, a pregnancy condition that can cause high blood pressure and other problems for the mother and baby. The treatment being used is acetylsalicylic acid, also known as aspirin. The purpose of the study is to find out whether stopping aspirin between weeks 24 and 26 of pregnancy works as well as continuing it until week 36 for preventing preterm preeclampsia.

In the study, pregnant participants will take aspirin by mouth during pregnancy, and then one group will stop it earlier while the other group will continue it longer. The study will then compare the two approaches to see whether stopping aspirin earlier is still safe for the mother and baby and whether it may lower the risk of bleeding in the mother.

1 start of the trial

Your trial participation begins after you join the study. The trial is designed to compare two ways of using acetylsalicylic acid, which is also called asa or aspirin.

The study focuses on preeclampsia, a pregnancy condition that can cause high blood pressure and other problems during pregnancy.

2 aspirin treatment during pregnancy

You take acetylsalicylic acid by mouth at a dose of 150 mg once daily.

One study group stops asa between week 24 and week 26 of pregnancy.

The control group continues asa until week 36 of pregnancy.

3 trial comparison period

The trial compares whether stopping asa at 24 to 26 weeks is no worse than continuing it until 36 weeks in preventing preterm preeclampsia, which means preeclampsia that happens before full term.

The trial also checks whether stopping asa changes the risk of problems for the mother, the baby during pregnancy, or the newborn, and whether it lowers the risk of bleeding in the mother.

4 end of the trial

The study is planned to run until 2028-12-30.

The trial does not describe any other treatment steps beyond the asa schedule and the comparison of outcomes during pregnancy and after birth.

Who Can Join the Study?

  • Be older than 18 years.
  • Be able to read and understand the informed consent, which is the written form that explains the study and must be signed before joining.
  • Have a singleton pregnancy, meaning one baby is being carried.
  • Have had first-trimester preeclampsia screening between 11 weeks 0 days and 13 weeks 6 days of pregnancy using a multiparametric algorithm, which is a screening method that uses several measurements and factors to estimate risk.
  • Be classified as high risk for preeclampsia on that screening.
  • Give voluntary informed consent, meaning agree freely and sign the consent form.
  • Be willing to follow the study protocol, including taking aspirin (ASA), having extra blood tests and ultrasounds, and following the treatment plan assigned at randomization, which means the treatment group is chosen by chance.

Who Cannot Join the Study?

  • Pregnancy loss early in pregnancy, a stillbirth (when the baby dies before birth), or a fetus with a major malformation (a serious problem in how the baby is formed).
  • A fetus with a known genetic disease or chromosomal disease (a condition caused by a change in genes or chromosomes).
  • A medical reason that makes aspirin unsafe to use, including a known allergy to aspirin or not being able to tolerate it because it causes harmful side effects.
  • Being unable to stop aspirin when required, such as in antiphospholipid syndrome (a condition in which the immune system increases the risk of blood clots and pregnancy problems).

Where you can join this trial?

Verified and Recommended Sites

No sites found in this category

Verified Sites

Site Name City Country Status
Hospital Universitario De Navarra Pamplona Spain
Hospital Jerez de la Frontera Jerez De La Frontera Spain

Other Sites

Site Name City Country Status
Hospital Universitario Puerta Del Mar Cadiz Spain
Hospital Universitari Dexeus Grupo Quironsalud Barcelona Spain
Hospital Universitario De Getafe Getafe Spain
Hospital Universitario Virgen De Las Nieves Granada Spain
Hospital Universitari Joan XXIII De Tarragona Tarragona Spain
Consorci Sanitari De Terrassa Terrassa Spain
Hospital Universitario Rey Juan Carlos Mostoles Spain
Hospital General Universitario De Alicante Alicante Spain
Hospital Universitario Severo Ochoa Leganes Spain
Hospital Universitario Clínico San Cecilio Granada Spain
Hospital Universitario De Cruces Barakaldo Spain
Hospital Universitario Fundacion Jimenez Diaz Madrid Spain
Hospital Universitario De Leon Leon Spain
University Clinical Hospital Virgen De La Arrixaca Murcia Spain
Hospital Universitari Arnau De Vilanova De La Gerencia Territorial De Lleida Lleida Spain
Hospital Universitari De Girona Doctor Josep Trueta Girona Spain
Fundacio Assistencial De Mutua De Terrassa Fpc Terrassa Spain
Area De Salud De Burgos Y Soria Burgos Spain
Hdjgpoiv Dy Lq Slyms Copw I Sdag Pnu Barcelona Spain
Hlnpssls Vkug dgqkdpkn Barcelona Spain
Haucsuwn Uoctmzbivhzic dq A Csiiys A Coruna Galicia Spain

Want to learn more about this study or check if you can participate? Contact us.

Trial status

Country Status Recruitment Start
Spain Spain
Not yet recruiting
30.01.2026

Trial locations

Investigated drugs:

Aspirin is the medicine being tested in this study. It is taken by mouth and is being used to help prevent preeclampsia, a pregnancy complication that can affect the mother’s blood pressure and the baby’s growth. In this trial, the researchers are studying whether stopping aspirin earlier in pregnancy works as well as continuing it later on to lower the risk of preterm preeclampsia.

Investigated diseases:

Preeclampsia – Preeclampsia is a pregnancy-related disorder marked by high blood pressure that develops after 20 weeks of pregnancy and is often accompanied by signs that the body is under stress, such as swelling or protein in the urine. It usually begins after a period of normal pregnancy and can appear gradually or more suddenly. In some cases, it progresses to a more severe form with worsening blood pressure and broader effects on the mother’s organs and the baby’s growth.

Trial ID:
2025-524646-94-00
Protocol code:
Optim-PRE26
Trial Phase:
Human Pharmacology (Phase I) – Other

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