3 months old baby wants to roll over, this is a normal physiological phenomenon, need to encourage the baby to roll over, rather than prevent. Generally 3 months old babies can hold their heads up more steadily, 4 months old babies can do a complete turn over, most 3 months old babies can turn over to the side from lying flat, usually you can let your baby lie down more, this can exercise the baby’s head up function, can exercise to the neck as well as the muscles of the back. If your baby keeps trying to turn over, you should also encourage your baby to lie flat on his back and use cards or toys to attract your baby’s attention as well as to guide turning over. Turning over can exercise the joints of the lower limbs, especially for the development of the hip joint is more beneficial, and is a good way to exercise the development of the lower limb muscles and waist muscles.