<prompt> All are risk factors for preterm delivery exceptAbsence of fetal fibronectin at 37 weeksPrevious history of preterm babyAsymptomatic cervical dilatationChylamydial infection of genital tract  <response>: Fetal fibronectin is a fetal glycoprotein that is expressed in the first half of pregnancy. After 20 weeks it is not normally detectable until membranes rupture. So its absence has been associated with a low risk of preterm delivery,whereas other 3 are obvious risk factors for preterm labour. TB of OBG Sheila 2nd edtn pg 192,193 