GDF15 and hydrops fetalis: Other emerging biomarkers that may predict cardiac involvement and the risk of heart failure (HF), such as interleukin-33R (IL-33R), which is also known as suppression of tumorigenicity 2 protein/interleukin-33R (ST2/IL-33R) and growth differentiation factor 15 (GDF-15), have been recently studied [23,24].