PTX3 and hydrops fetalis: Individually, five of the candidate biomarker proteins were significantly differentially expressed between HF and non‐HF patients: leucine‐rich‐alpha‐2‐glycoprotein (LRG1, P < 0.001), zinc‐alpha‐2‐glycoprotein (ZA2G, P = 0.001), serum paraoxanse/arylesterase (PON1, P = 0.006), Apolipoprotein A‐I (APOA1, P = 0.009 and P = 0.038), and pentraxin 3 (PTX) (Table2, P = 0.049).