It is normal for a 2-month-old baby to have an inward thumb. The thumb is flexed inward and the rest of the fingers are wrapped around the outside of the thumb. For a newborn baby, the body’s nervous system is not yet fully developed, and at this time the flexor muscles are mainly dominant and the extensor muscles are not particularly developed, thus showing an inward thumb. As the baby’s thumb is buckled, the baby’s finger mobility is not particularly flexible, so the newborn baby is not yet able to carry out fine grasp, grip, pinch and other actions. Generally, as the age of the baby increases, the nervous system gradually begins to develop and mature. 3-4 months old, the baby’s flexor muscle no longer dominates, but gradually the extensor muscle dominates, at which time the muscle strength and muscle tone gradually decreases, and the phenomenon of the thumb buckle will gradually decrease and disappear. If your baby is more than 4-6 months old and still has the phenomenon of inward thumb clasp, you should be aware that there may be an increase in muscle tone, and you should immediately take your baby to the hospital for a detailed examination, including the development of the central nervous system, muscle strength, muscle tone and gross motor development. If the baby is considered to have abnormal muscle tone, cerebral palsy or delayed brain development should be considered. In this case, a CT or MRI of the head should be performed in a timely manner to clarify the cause of the neurological delay, and if necessary, screening for genetic metabolic diseases should be performed to clarify the diagnosis and provide timely targeted treatment. In addition, you can let your baby practice finger grasping and gripping in daily life to promote the growth and development of local muscles.