During the breastfeeding period, the sudden reduction of milk is mainly related to the following three reasons: First, when the mood is low or excessive mental tension, it will affect the release of hypothalamic pituitary hormones, resulting in insufficient milk secretion, causing a reduction in milk. This is mostly a temporary decrease in milk, which can be normalized after treatment. Secondly, wearing too tight chemical fiber underwear, resulting in localized pressure on the nipple, causing blockage of the mammary ducts, milk stagnation, the phenomenon of milk reduction. Third, due to the decrease in the number of times the baby sucks on the nipple, resulting in a decrease in the secretion of prolactin and a decrease in milk production. Fourthly, due to unplanned pregnancy during breastfeeding, resulting in hormonal disorders, milk secretion is reduced. All in all, do not panic when there is a sudden decrease in milk, you should go to the regular hospital, clear the reason for the decrease in milk, and active treatment, more can make milk secretion increase. At the same time, during the breastfeeding period, you should wear loose, breathable underwear, and eat more food rich in protein and vitamins.