A large number of studies on MVs from syncytiotrophoblasts support the hypothesis of their involvement in pre-eclampsia, via their multiple effects, among others as pro-coagulant, immuno-stimulatory and anti-angiogenic factors.

The main objective is to compare the total concentration of the main populations of MVs in the maternal blood of a population of pre-eclamptic patients to those of a population of non-pre-eclamptic patients.

Activated or apoptotic cells release membrane fragments called microvesicles, microparticles, extracellular vesicles or exosomes into the extracellular environment. The term microvesicle (MV) used in this project encompasses all membrane fragments secreted by cells, regardless of their cellular origin, their size or the membrane compartment from which they originate.

The presence on the surface of MVs and in their reservoir of elements from their parent cell, such as surface receptors, mRNAs or microRNAs, led to the hypothesis that MVs could serve as biomarkers, revealing the existence of tissues in distress in the body.

Under physiological conditions, blood plasma contains mainly MVs from red blood cells and platelets, the main circulating cell populations. During pregnancy, the presence of membrane fragments of placental origin in the maternal circulation has long been established. A large number of studies on syncytiotrophoblast-derived MVs support the hypothesis of their involvement in pre-eclampsia, via their multiple effects, among others as pro-coagulant, immuno-stimulatory, anti-angiogenic factors.

The "Membrane Repair and Extracellular Vesicles" team within the CBMN laboratory of the University of Bordeaux has developed original approaches to characterize and quantify MVs, mainly by cryo-electron microscopy, immunogold labeling and flow cytometry. In addition, recent developments from this team allow the analysis of MVs in whole blood, which is a major advantage.

The main objective is to compare the total concentration of the main populations of MVs in the maternal blood of a population of pre-eclamptic patients to those of a population of non-pre-eclamptic patients.

Inclusion Criteria:

• Age ≥ 18 years
• Singleton pregnancy (or spontaneously reduced twin pregnancy before 14 SA)
• Gestational age at inclusion between 23 and 31+6 SA
• Collection of the patient's non-opposition
• Affiliated or beneficiary of a social security system
• Specifically for the non-pre-eclampsia group: non-pre-eclamptic patient hospitalized for isolated threat of preterm delivery, whatever the origin, and without clinical (absence of maternal hyperthermia defined by a maternal temperature < 38.0°C) or biological markers of inflammation (CRP<5)
• Specifically for the pre-eclampsia group : diagnosis of severe pre-eclampsia before 32 weeks' gestation

Exclusion Criteria:

• Patient's inability to understand the nature, risks, meaning and implications of the clinical investigation or refusal to give consent
• Patient under legal protection.