1. Development indicators of height and weight After the baby is born, the height and weight develop very quickly. By 9 months, the baby\’s height will generally increase to about 1.5 times that of birth, and the weight will increase to about 2.5 times of birth. Babies at this stage need to consume approximately 900 kcal per day to support their rapid growth. 2. Movement ability and hand-eye coordination As babies continue to grow, their movement ability will become stronger and stronger. By 9 months, most babies have learned to roll, crawl, and sit up. this