A sudden decrease in milk production in newborns may be due to physiological factors such as uncomfortable temperature of the breastfeeding environment, or it may be caused by illnesses such as colds and sepsis. 1. Physiological factors: physiological factors such as a newborn’s breastfeeding environment being too cold or too hot may lead to a sudden decrease in milk production. 2. Pathological factors: when a newborn has a cold, sepsis and other diseases, it is often accompanied by fever, reduced digestive function and other symptoms, which in turn affects the newborn’s appetite, leading to a decrease in milk supply. For newborns who have a sudden decrease in milk production, they should go to a regular hospital in time to clarify the cause of the disease and be treated under the guidance of the doctor.