Newborns do not grow weight, common causes are physiological weight loss, improper feeding, but also can be seen in disease states, such as congenital heart disease, hypothyroidism and so on. 1. Physiological weight loss: after the birth of the baby, the loss of excessive body fluids within 1 week of birth leads to physiological weight loss, generally not more than 10% of the body weight, physiological weight loss is mostly recovered in about 10 days. 2. Improper feeding: Insufficient breast milk, improper feeding or poorly fed baby can also lead to weight loss. 3. Disease state: the child has congenital heart disease, hypothyroidism, or the presence of infection, aspiration pneumonia, resulting in excessive energy consumption, may not gain weight. Newborns do not grow weight, there may be other reasons, it is recommended to go to the hospital in time, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.