Fig. 2.

PCA score plot of all samples in ESI+  (a) and in ESI− (b) and respective volcano plots (c and d). In PCA plots, blue dots represent sPTB case samples, yellow triangles represent control samples, and grey squares represent QC samples. Volcano plots show log₂ fold change plotted against –log₁₀ of adjusted p values in ESI+  (c) and ESI − (d), plotted in blue are the variables with an adjusted p value < 0.05