PGF and preeclampsia: In comparison with the mild preeclampsia group, the HDCP group illustrated elevated serum PECAM-1 and PLGF levels, and depleted RI, PI, and S/D; in comparison with the mild preeclampsia group, the severe preeclampsia group illustrated depleted serum PECAM-1 and PLGF levels, and elevated RI, PI, and S/D (p < 0.05; Figure 4).