The investigators project aims to identify, in pregnant women, discriminating molecules to allow an early detection of women who will spontaneously deliver prematurely, suitable in routine clinical practice.

Human parturition is tightly correlated with hormonal changes at the maternal-fetal interface during pregnancy, that may control cell interactions and fetal membranes (the water bag) remodelling. Precocious remodelling may lead to a premature onset of labor, associated or not with premature rupture of membrane whether the cause is infectious or not.

In this regard, remodelled fetal membranes overlying the cervix may discharge signals that could be detectable in cervico-vaginal fluids and serve as biomarkers of the imminence of delivery. Such information on delivery timing may be of great importance for an adequate prediction that would change drastically the management of threatening preterm delivery.

Prematurity is a major Public Health concern in developed countries, since it is the first cause of perinatal morbi-mortality and of cerebral palsy in early childhood. Premature birth rate has risen by 36 percent over the last 25 years to reach 7.2% in 2010 in France. Antenatal corticosteroids administration before 34 weeks and in utero transfer in high-qualified maternity wards are ones of the rare antenatal therapies recommended to improve neonatal complications of preterm delivery. Early identification of women with high risk of preterm birth should be helpful to implement those prophylactic measures. Moreover discriminating true preterm labor (PTL) vs. symptoms of PTL in women, who will finally deliver at term, would reduce unnecessary hospitalizations and prescriptions.

During human gestation, fetal membranes (the "water bag") encompass the amnion, facing the amniotic cavity, and the chorion, lining the maternal decidua and comprising trophoblast cells. Membranes usually remain intact until their spontaneous rupture, close to the first stage of labor at term. Often seen as a simple inert shell, with a role of "airbag" for the developing fetus, the membranes provide yet a large surface of interaction between maternal and fetal tissues and function as a transient endocrine organ with immune properties.

Specific remodelling of the membranes is observed at term prior to delivery. During this remodelling, drastic changes in extracellular matrix occur, with the secretion of specific molecules. The investigators hypothesize that premature fetal membranes remodelling occurs weeks prior to actual birth and may be able to be detected in women at risk for preterm birth, i.e. presenting signs of PTL. This study investigates if the detection of fetal membranes remodelling in cervico-vaginal fluids can accurately identify those women at greatest risk for preterm birth. A prospective cohort of pregnant women will before 32 weeks of gestation with symptoms of preterm labor be enrolled. As negative controls, healthy pregnant women at 12-15 or 35-36 weeks of gestation or non-pregnant women will be recruited. As positive controls, healthy pregnant woman at term (over 38 weeks of gestation) will be enrolled. The main outcome assessed is preterm delivery.

Inclusion Criteria:

- Singleton pregnancy, monitored in Port Royal or secondarily transferred, between 24 and 32 GA. Hospitalization for preterm labor (cervix < 25 mm at transvaginal cervical ultrasound) or -Singleton pregnancy, monitered in Port Royal between 15-16 weeks of gestation, without complication.

or - Singleton pregnancy, monitered in Port Royal between 35-36 weeks of gestation, without complication.

or - Healthy woman, no pregnancy.

Exclusion Criteria:

• Minor
• Not affiliated to health insurance
• Persons under guardianship or judicial protection
• Infection with HIV, Hepatitis B Virus (HBV) or Hepatitis C Virus (HCV)
• Diabetes or chronic inflammatory disease
• Carrier of B streptococcus
• Cervical strapping
• Fetus with chromosomal abnormalities
• Infections
• Premature rupture of membrane