SPTB and preterm premature rupture of the membranes: At 14–15+6 weeks, CVF Cathelicidin was moderately predictive of sPTB < 37 weeks (ROC 0.67, 0.61 to 0.74), < 34 weeks (n = 229, ROC 0.63, 0.56 to 0.69) and PPROM (n = 225, ROC 0.64, 0.58 to 0.71) but not at other sampling timepoints, nor for adverse fetal or maternal outcomes.