Читать книгу Lifespan Development - Tara L. Kuther - Страница 346

As compared with the first 2 years of life, growth slows during early childhood. From ages 2 through 6, the average child grows 2 to 3 inches taller and gains nearly 5 pounds in weight each year. The typical 6-year-old child weighs about 45 pounds and is about 46 inches tall.

Biological factors play a large role in physical development. Children’s height and rate of growth are closely related to that of their parents (Kliegman et al., 2016). Genes influence the rate of growth by stipulating the amount of hormones to be released. Hormones are chemicals that are produced and secreted into the bloodstream by glands. One hormone, growth hormone, is secreted from birth and influences the growth of nearly all parts of the body. Children with growth hormone deficiencies show slowed growth, but growth hormone supplements can stimulate growth when needed (Stagi, Scalini, Farello, & Verrotti, 2017).

Ethnic differences in patterns of growth appear in developed nations such as England, France, Canada, Australia, and the United States (Natale & Rajagopalan, 2014). Generally, children of African descent tend to be tallest, followed by children of European descent, then Asian, then Latino. However, there are many individual differences. Even within a given culture, some families are much taller than others (Stulp & Barrett, 2016). It is difficult to assess ethnic differences in growth patterns of children in developing nations because malnutrition and growth stunting are common (de Onis & Branca, 2016). In addition, there is little research examining normative patterns of development in developing countries.