ACHE and hydrops fetalis: When HF occurs, acetylcholine is released more from the postganglionic nerve fibers of the cardiac vagus nerve in HF to activate the AChE and acetylcholine M receptors, mainly the M2 receptor in the heart, which could regulate the expression of inflammatory factors, thereby protecting cardiomyocytes (Cheng et al., 2021; Zhang et al., 2021).