The reasons why 5-month-old babies will not roll over can be divided into physiological and pathological reasons. 1. Physiological factors: if you do not give your baby timely turn over training, 5-month-old babies often take the position of lying down, side-lying, there is no opportunity to turn over, may not turn over. 2. Pathological factors: commonly found in premature babies, low birth weight babies, calcium deficiency or suffering from cerebral ischemia and hypoxia, microcephaly and other diseases of the baby, at this time, 5 months of the baby usually will not roll over, and will not smile, compared with children of the same age, growth and development is delayed or backward, seriously does not conform to the law of development, the muscle strength is not enough to support the movement of rolling over. 5-month-old babies will not roll over usually need to be handled in a timely manner, and at the same time, regular physical examination should be conducted, if problems are found should be actively treated.