SFRP2 and hydrops fetalis: As expected, the median concentration of SFRP2 (22.97 ng/mL vs. 7.43 ng/mL, respectively) and NT-proBNP (3439.00 pg/mL vs. 64.43 pg/mL, respectively) were significantly higher in the HF group than those in the control group (both P < 0.001).