SPTB and preterm premature rupture of the membranes: As PLS-DA did not show clear discrimination between SPTB and PPROM, PNN analysis of all the metabolite bins was conducted between sPTB cases combined (PPROM and SPTB) and controls at week 16 gestation and showed moderate predictive power AUC = 0.77 (LOOCV) (Supplementary Table S1).