Since we previously found that FGF23/FGFR4 signaling in cardiac myocytes induces cardiac hypertrophy by activating calcineurin/NFAT signaling [23,34], which has been shown to act as an inducer of pregnancy-associated cardiac hypertrophy [35], we aimed to determine whether FGFR4 is required for the development of physiologic cardiac hypertrophy in pregnant mice and to identify the source of FGF23 in pregnancy. The gene discussed is FGF23; the disease is cardiac hypertrophy.