The following causes can lead to back milk: 1. over fatigue reduces the amount of milk production. 2. lack of sleep can also reduce the amount of milk production. 3. taking a certain drug can lead to a reduction in the amount of milk and can have a back milk effect, such as taking a tonic jelly or drinking fried malt water, which may lead to a significant reduction in the amount of milk. 4. a sudden emotional shock and mental unhappiness can also lead to a sudden decrease. It is recommended that during the breastfeeding period, you must live a regular life, pay attention to rest, strengthen nutrition in your diet, and drink more soups, like chicken soup, fish soup, meat soup, etc., which will increase the secretion of breast milk. In addition, if you do not have milk allergy, you can also drink more milk, which can enhance the secretion of milk.