Preeclampsia may have several causes leading to different characteristics of the pathology. Differentiation between the "type of preeclampsia" would help to treat patients more accurately. This project aims to identify early markers that are specific to each type of preeclampsia (early or late, with or without growth restriction). Through a case-control study, many data will be collected prospectively (serum markers, ultrasonographic markers, maternal factors) among nulliparous women with no sign of preeclampsia (as soon as the first trimester) and nulliparous women with preeclampsia (at diagnosis).

Background: The current definition of preeclampsia is based on signs and symptoms without reference to the pathology. The majority of preeclampsia cases would come from placental dysfunction beginning early in pregnancy, even before the onset of clinical or biochemical events leading to the diagnosis. Defects in the development of the placenta (impaired transformation of the spiral arteries) would seem to lead to poor placental perfusion. Currently, the uterine artery Doppler is the marker used to predict placental perfusion in routine monitoring of the pregnant woman. However, other placental aspects, such as the ultrasonographic measurement of placental volume could also be useful for predicting preeclampsia. Also, several studies have shown that many blood markers (PAPP-A, PlGF, sFlt-1) detected as soon as the first trimester seem effective to predict the majority of early pre-eclampsia, those occurring before 34 weeks of gestation. However, the predictive value of these markers is not so strong regarding prediction of later preeclampsia, those occurring between 34-37 weeks and at term.

Other studies show that some maternal factors, including the value of arterial pressure, BMI, maternal age, could contribute to screening for pre-eclampsia. Recent studies have also been interested in the maternal ophthalmic artery Doppler to try to predict preeclampsia even before the development of clinical symptoms.

Our hypothesis is that each of these biomarkers may be specific to a certain type of pre-eclampsia (early or late; with or without intra uterine growth restriction). We believe that actual definition of preeclampsia includes heterogenous causes and that better understanding of this pathology would help practicians to offer a more individualised treatment to their patients.

Objective: Our main goal is to characterize from a biophysical, biochemical, ultrasonographic and placental perspective the pathology of preeclampsia.

Method: This case-control study will recruit:

1. nulliparous women at 1st trimester of pregnancy. They will provide blood sample and U/S examination at 4 different times during pregnancy.
2. nulliparous women at diagnosis of preeclampsia.

Data that will be collected are:

maternal age maternal BMI maternal ethnicity maternal mean arterial pressure (at recruitment/diagnosis and delivery) gestational age at recruitment/diagnosis and at delivery maternal serum PAPP-A, PlGF, endoglin, sFlt-1 (at recruitment and delivery) cord blood PlGf, endoglin, sFlt-1 fetal crown-rump length at 1st trimester (at recruitment) fetal growth (during pregnancy) Uterine arteries Doppler Cord arteries Doppler Maternal Ophthalmic arteries Doppler Placental volume newborn birthweight

Inclusion Criteria:

• Nulliparous women (no previous delivery ≥ 20 weeks)
• Expect to deliver in recruiting center
• Control group: recruited between 11 - 13 6/7 weeks of gestation
• Case group: recruited at time of diagnosis of preeclampsia > 20 weeks of gestation

Exclusion Criteria:

• multiple pregnancy
• pregnant women <18 years old at recruitment

Nulliparous pregnant women