Diet trap
Malnutrition, qi and blood deficiency, etc. It may make the milk "run away from home". And some milk-returning foods, such as leeks and pepper aniseed, may also become "behind-the-scenes pushers".
Breast "traffic jam"
Wearing too tight underwear, mood swings, and eating greasy food during lactation may all cause blockage of the mammary duct and make the milk "unable to flow out".
Body "red light"
If the new mother is unwell, such as a fever and a cold, it may affect the secretion of milk and make the milk "thin".