ADRB2 and hydrops fetalis: Although metoprolol causes cardiac fibrosis, it remains useful in the management of HF patients (Kukin et al., 1999) since metoprolol attenuates the effect of catecholamine overstimulation in the patients’ hearts and metoprolol-induced fibrosis is neglectable compared with βAR-induced fibrosis (Nuamnaichati et al., 2018) and HF-induced fibrosis.