4 months baby will not roll over, there are normal and abnormal two kinds of cases, each baby’s motor development there are some individual differences, need to measure the overall motor development to assess, specific analysis is as follows: 1. Normal: If the baby’s head is very stable, at the same time, the ability to catch up with the sound, catch up with the same age of the baby are basically the same, just turn over this action is more difficult, may be due to the parents of the training is too little or the baby is too fat caused by this kind of belong to the normal. 2. abnormal: if the baby will not turn over in addition to other large motor development is also significantly behind the same month of age baby, may be caused by delayed motor development, calcium deficiency, myasthenia gravis and other diseases. 4 months baby will not roll over, there may be other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, give targeted treatment or treatment.