The baby suddenly not sucking breast milk may be physiological anorexia, or functional dyspepsia, thrush and other diseases. 1. Physiological anorexia: mostly seen in 3 to 4 months of the baby, mainly because of this stage of the baby’s growth and development rate significantly lower, the body’s demand for nutrients and energy less, so the baby will suddenly not breastfeeding. 2. Functional dyspepsia: Clinical belief that the occurrence of this disease is the result of genetics, Helicobacter pylori infection, high sensitivity of internal organs, eating too fast and other factors, the main symptoms of loss of appetite, flatulence, etc., some of the symptoms of severe children will suddenly not breastfeeding. 3. Thrush: this disease is mainly caused by the oropharyngeal Candida overproliferation, often due to low immunity, long-term use of antibiotics and other factors and triggered, resulting in children with irritability, crying, breastfeeding difficulties and other symptoms, can be manifested as a sudden not sucking breast milk. There may be other reasons why a baby suddenly stops sucking breast milk, so it is recommended to go to the hospital in time, complete the examination to clarify the cause of the disease, and then give targeted treatment or therapy under the guidance of the doctor.