TH and hydrops fetalis: In recent years, numerous clinical studies have shown a significant association between low thyroid hormone (TH) function and worsening cardiac function, and increased mortality in heart failure (HF; Tseng et al., 2012; Mitchell et al., 2013; Chuang et al., 2014; Wang et al., 2015; Brozaitiene et al., 2016; Gil-Cayuela et al., 2017, 2018; She et al., 2018; Sato et al., 2019).