What is the height standard for a one- and two-year-old baby? According to the World Health Organization (WHO) child growth and development standards, the average height of a two-year-old boy is 86.4 cm and the average height of a girl is 84.6 cm. However, it should be noted that each child\’s growth and development is different, so you should not be too rigid in standard values. 2. What are the factors that affect the height of a two-year-old baby? 1. Genetic factors: A child’s height is related to the height of his parents and grandparents. 2. Nutrient intake: Adequate and balanced nutrition is crucial to the growth and development of children. 3. Exercise: Proper exercise can promote bone and muscle development.