GDF15 and hydrops fetalis: GDF15 was inversely related to tricuspid annular plane systolic excursion (TAPSE) and the six-minute walking test (6MWT), and positively related to hallmarks of HF [i.e., N-terminal prohormone of brain natriuretic peptide (NT-proBNP)] and other molecules influenced by HF progression [i.e., creatinine and ferritin].