All are risk factors for preterm delivery except
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)
Absence of fetal fibronectin at < 37 weeks
Previous history of preterm baby
Asymptomatic cervical dilatation
Chylamydial infection of genital tract
Abnormal labor