Changes in the 3rd month of life include height, weight, cervical spine, and cognition. As babies grow, all aspects continue to change. For babies in their 3rd month of life, their height, weight, and head circumference have all grown considerably. Their height can grow by about 12cm and their weight is likely to be twice as much as at birth. At 2 to 3 months of age, babies may slowly appear to raise their head. For babies with better cervical vertebrae, you can slowly hold your baby upright. In addition, in the 3rd month of life, the baby can obviously have a laugh, and at this time, the baby can be teased to hear him/her make a laughing sound. In addition, the third month of life of the baby if the early discovery of abnormalities, the need to go to the hospital pediatrics in a timely manner.