The average weight of a 3-month-old male baby is about 6.4kg, with a normal range of 5.0kg-8.0kg, and that of a female baby is about 5.8kg, with a normal range of 4.5kg-7.5kg. For artificially fed babies, the weight increases by about 600g per month. The average height of male babies is about 61.4cm, the normal range is 57.3cm-65.5cm, the average height of female babies is 59.8cm, the normal range is 55.6cm-64cm. the average head circumference of male babies is about 40.8cm, the average head circumference of female babies is about 39.8cm, the head circumference is a direct symbol of brain development, directly affecting the baby’s future intellectual development. The head circumference is a direct symbol of brain development and directly affects the future intellectual development of the baby. At this time the baby’s hands will grasp clothes, hair, often sucking their fingers, baby’s fingers touch the mouth, in the reflex role will suck, will allow the baby to get a similar sense of security sucking breast.