NPPB and hydrops fetalis: HFrEF: heart failure with reduced ejection fraction, defined in this study as ejection fraction less than 50%; LVEF: left ventricular ejection fraction; HFpEF: heart failure with preserved ejection fraction; HF: heart failure; BMI: body-mass index, which is the weight in kilograms divided by the square of the height in meters; BNP: brain natriuretic peptide used as a marker for heart failure.