SERPINF1 and hydrops fetalis: However, the metformin group exhibited decreased serum PEDF levels (2.16 ± 0.09 versus 1.69  ±  0.24 μg/mL, P < 0.05, Figure 2(a)) and down-regulated PEDF expression when compared with the HF group (Figures 2(c) and 2(d)).