FN1 and preterm premature rupture of the membranes: Clinical history is a poor-to-fair predictor of PTB by AUC [17], and the measurement of cervical fetal fibronectin (fFN) or CL at 16–22 weeks yields AUCs for sPTL/PPROM ≤ 32 weeks of 0.51–0.54 and 0.51–0.58, respectively [6].