CD4 and hydrops fetalis: T cells CD8 (P = 0.0028), mast cell resting (P < 0.001) were significantly increased in the HF disease group, and the cell subtype with low expression in HF tissues was T cells CD4 memory resting (P = 0.017), T cells regulatory (Tregs) (P = 0.047), monocytes (P < 0.001), and macrophages M2 (P < 0.001).