Validation of the identified core regulatory genes associated with ICP pathogenesis by qPCR. Genes with expression patterns in placental tissues from healthy group, mild ICP, and severe ICP (10 pregnancies per group) consistent with those in the microarray data are shown: Genes involved in (A) immune response, (B) VEGF signaling and (C) G-protein-coupled receptor (GPCR) signaling. Relative expression of each target gene was normalized to GAPDH, and expression levels in the healthy group were defined as 1. All reactions were performed in triplicate, and data are presented as mean ± s.d. (n = 10). *p < 0.05; **p < 0.01; ***p < 0.001; NS, not significant. Primer pairs used were listed in Additional file 1: Table S1.