The growth of the foetus and its size at birth depend on: the health and nutritional status of the mother; the uterine circulation and placenta; and problems and disorders in the baby. After birth, the growth of the baby depends on different factors. In the first year or two of life, growth hormone (GH) is thought to play only a small part in the pattern of growth, but gradually this increases. During the rest of childhood GH is the most important single factor – other than nutrition – in determining growth. Conventional growth charts compare parameters such as height, weight, and rate of growth, with what is observed in the whole population. Breastfed babies show a slightly different growth pattern from formula-fed babies. Assessment of growth is an important part of any child protection assessment. Children with hormonal deficiencies and other disorders affecting growth need treatment as early as possible.