Three-month-old baby if the premature baby neck and waist are very soft may belong to the normal phenomenon, if it is a full-term baby belongs to the abnormal phenomenon, need to be determined according to the specific situation, it is recommended that the hospital consultation, clear cause of the disease and timely treatment. If the baby is born at full term, the head is usually better lifted at three months, and the neck and waist are stiffer. If the neck and waist are still soft at this time, it may be caused by low muscle tone and poor brain development. If the baby is preterm, three months, the neck and waist is still a little soft, it may be a normal phenomenon, because preterm babies weight development than full-term babies later than the development of the nervous system is not sound, so to the age of three months, there may be the neck and waist is still soft, this is normal. Therefore, if your baby’s neck and waist are soft or accompanied by other abnormalities in the third month of life, you need to make a comprehensive judgment based on the specific situation. It is recommended to go to the hospital as soon as possible to confirm the diagnosis, clarify the cause of the disease and guide the treatment.