The disclosure provides a pair of isolated biomarkers selected from the group consisting of IBP4 / SHBG, IBP4 / PSG3, IBP4 / LYAM1, IBP4 / IGF2, CLUS / IBP3, CLUS / IGF2, CLUS / LYAM1, INHBC / PSG3, INHBC / IGF2, PSG2 / LYAM1, PSG2 / IGF2, PSG2 / LYAM1, PEDF / PSG3, PEDF / SHBG, PEDF / LYAMl, CD14 / LYAM1, and APOC3 / LYAM1, wherein the pair of biomarkers exhibits a change in reversal value between pregnant females at risk for pre-term birth and term controls. Also provided is a method of determining probability for preterm birth in a
pregnant female, the method comprising measuring in a biological sample obtained from the
pregnant female a reversal value for at least one pair of biomarkers selected from the group consisting of IBP4 / SFIBG, IBP4 / PSG3, IBP4 / LYAM1, IBP4 / IGF2, CLUS / IBP3, CLUS / IGF2, CLUS / LYAM1, INHBC / PSG3, INHBC / IGF2, PSG2 / LYAM1, PSG2 / IGF2, PSG2 / LYAM1, PEDF / PSG3, PEDF / SHBG, PEDF / LYAMl, CD14 / LYAM1, and APOC3 / LYAM1 to determine the probability for preterm birth in the
pregnant female.