NPPB and hydrops fetalis: For instance, Cheng et al. 14 have performed untargeted metabolomics analysis followed by targeted evaluation of obtained results and an identification of a combination of four metabolites (histidine, phenylalanine, spermidine, and phosphatidylcholine C34:4) that discriminated HF stage C from control group similarly to b-type natriuretic peptide (BNP).