Early pregnancy prediction of spontaneous preterm birth before 32 completed weeks of pregnancy using plasma RNA: transcriptome discovery and initial validation of an RNA panel of markers

Objective To compare the second‐trimester plasma cell‐free (PCF) transcriptome of women who delivered at term with that of women with spontaneous preterm birth (sPTB) at or before 32 weeks of gestation and identify/validate PCF RNA markers present by 16 weeks of gestation. Design Prospective case–control study. Setting Academic tertiary care centre. Population Pregnant women with known outcomes prospectively sampled. Methods PCF RNAs extracted from women at 22–24 weeks of gestation (five sPTB up to 32 weeks and five at term) were hybridised to gene expression arrays. Differentially regulated RNAs for sPTB up to 32 weeks were initially selected based on P value compared with control (P