Maternal Plasma Biomarkers for Preterm Birth

The current study included all available plasma samples from women who met our inclusion criteria (n = 1115 plasma samples, n = 326 women). Maternal peripheral plasma samples were collected in EDTA and stored at −80 °C unthawed until testing. Plasma samples were processed using enzyme-linked immunosorbent assays (Duosets, R&D Systems, Minneapolis, MN) listed with dilution factors: CHI3L1 (1:1000), CRP (1:8000), IL-18BP (1:20), IL-6 (1:20), sICAM-1 (1:500), and sTNFR2 (1:200). The markers were selected based on previous studies reporting an association with MiP and PTB^{20 (link),24 (link),35 (link)}. Processing and analysis of samples was performed according to the manufacturer’s instructions and blinded to treatment group and outcome.