Infants who are underfed may have abnormalities such as poor sleep quality, developmental delay and low resistance. 1. Poor quality of sleep: Due to insufficient feeding, the child develops a sense of hunger, and will often suffer from sleeplessness, poor quality of sleep, frequent crying, etc., which cannot be relieved even after being picked up and soothed, and the prolonged period of poor quality of sleep will also have an impact on the child. 2. Developmental delay: Insufficient feeding will lead to infant developmental delay, length and weight lower than normal infants, the lack of vitamin D in the body may also lead to deformities of the bones, rickets, so the feeding of infants should be strengthened in daily life. 3. Low resistance: Inadequate feeding of infants will lead to the lack of nutrients, decreased immunity, colds, coughs and other symptoms, and in severe cases will lead to iron-deficiency anemia, which should be ensured in the daily intake of infants. Inadequate feeding can lead to a variety of symptoms in infants, it is recommended to seek timely medical treatment, standardized treatment and breastfeeding.