PON1 and hydrops fetalis: G2 levels (TETRA 2.70 ± 1.04 mg/L, PON1 7.16 ± 1.98 U/L) reflect reductions consistent with heart failure, as observed in McDonald et al. (2020) [17] for TETRA and Hammadah et al. (2017) [26] for PON1 (CHF range 52–111 U/L), supporting their relevance across HF severity and enhancing generalizability despite our single-center cohort.