Infant thumb always hold in the heart of the hand is considered to be physiological factors, may also be the emergence of cerebral palsy and other diseases. 1. Physiological factors: some babies in the process of growth and development due to the imperfect development of the nervous system, the existence of the grip reflex, there may be a hand clenched fist symptom, especially 1 ~ 2 months or so babies will appear this symptom, is generally normal, the baby’s growth and development basically will not have an impact. 2. Cerebral palsy: a small number of babies often hold their thumbs in their hands may be related to cerebral palsy, such as spastic quadriplegia, mainly cone damage, can be manifested as increased muscle tone in the limbs, thumb inward, trunk tilt and other manifestations. If your baby shows signs of cerebral palsy, it is best to actively seek medical examination and treatment.