Three years and eight months old boys are usually between 98.6-105.8cm in height and 13.6-18kg in weight. The height and weight are different because every child has different physical qualities and genetics. The typical height for a 3 year old 8 month old boy is between 98.6-105.8cm and weight is between 13.6-18kg. if the child’s height and weight are within this range, no treatment is needed. If your child’s height and weight are below the normal range, you can ensure the nutritional intake needed by your body through a proper diet, and ensure the quality of your child’s sleep and sleep environment. Take your child to the sun more often to promote the production of vitamin D. You can also increase outdoor activities and physical exercise as appropriate. If the symptoms are not relieved after lifestyle modification, you should consult a doctor in time to clarify the cause of the disease and carry out treatment under the guidance of the doctor.