Many newborns will have an inward clenching of the thumb, and the determination of whether this is normal or not is based on the child’s specific situation. The first belongs to the normal phenomenon, if the child clenches the fist thumb in the degree of internal buckle is relatively mild, the thumb clenched fist is easy to break, and does not exceed the level of the middle finger line, belongs to the normal muscle tone increased. Because newborns are young, the brain is not mature, the control of the surrounding muscles is relatively low, so there will be a temporary increase in muscle tone, and will slowly disappear when the child gets older. If the child’s fist clenching and thumb clenching are heavy and difficult to break with force, and the thumb clenching exceeds the middle line of the middle finger, and there is also increased muscle tone in the lower extremities, this situation should be considered cerebral palsy.