NPPB and hydrops fetalis: The number of risk factors did not differ between HF stages and median plasma concentrations of the cardiac biomarker N-terminal pro-brain natriuretic peptide (NT-proBNP) increased with higher HF-stage (stage A 132.5 ng/L; stage B 275.5 ng/L; stage C 400.0 ng/L, P < 0.001).