The area under the ROC curve for the prediction model was 0.67 and expressed moderate effectiveness.[16] Chiu et al found that low levels of maternal serum placental growth factor (PlGF) and PAPP-A in the first trimester were associated with an increased risk of PPROM in pregnant women < 37 gestational weeks. This evidence concerns the gene PAPPA and preterm premature rupture of the membranes.