Three-month-old babies begin to have a rudimentary understanding of the outside world, and their ability to move at will begins to develop as the central nervous system, bones and muscles continue to grow. During this period, toddlers generally begin to perceive the world with their eyes and master simple movements such as smiling, shaking hands and lifting their heads. At this time, children can recognize their parents’ faces and smells, hold their heads steadily, follow moving objects with their eyes, and squeak and make “gurgling” and “cooing” sounds. In terms of body movement, toddlers can roll over from prone to supine, turn their heads when they hear loud noises, and put their hands together to slap toys with their hands. Parents do not need to worry if their toddlers cannot do this for the time being, as the developmental level of each toddler varies and this is completely normal. In addition, toddlers grow rapidly in height and weight at three months. Weight is usually double that at birth, with male babies usually 5.1-7.9 kilograms and female babies usually 4.6-7.4 kilograms. For height, male babies are usually 57.6-65.3 centimeters and female babies are 55.9-63.8 centimeters. If a toddler’s height and weight growth are not satisfactory, it may indicate insufficient feeding and parents should pay attention to it and improve feeding or seek medical consultation in time.