FGF23 and hydrops fetalis: In multivariable Cox regression analysis, FGF23 [adjusted hazard ratio (HR) 1.665; 95% confidence interval (CI) (1.284–2.160; P < 0.0001)], B‐type natriuretic peptide (HR 1.433; CI 1.053–1.951; P = 0.022), and prior HF hospitalization (HR 2.058; CI 1.074–3.942; P = 0.030) were independent predictors of the composite endpoint.