OBJECTIVES : Primary To seek link between the respective proportions of circulating maternal monocyte and lymphocyte subpopulations and the true onset of PTL characterised by delivery occurring within 7 days post admission. Secondary: to (1) compare the predictive values of these new markers with those currently used, e.g. quantification of fœtal fibronectin and assessment of cervical length and effacement, (2) Compare the respective proportions of monocytes and lymphocyte subpopulations in maternal blood and fœtal membranes, (3) determine if a correlation exists between the activation markers expressed by maternal monocyte and lymphocyte subpopulations and the neonatal outcomes of preterm infants.