NPPB and hydrops fetalis: B‐type natriuretic peptide (BNP) is a peptide hormone that is now the gold standard diagnostic and prognostic biomarker for HF.17 Indeed, a systematic review of 19 studies reported that, for every 100 pg/mL rise in BNP concentration, there is a corresponding 35% increase in the risk of death, and recent updates of the ACC/AHA/HFSA and ESC guidelines recommend using BNP levels in the risk stratification of HF.1, 9