Читать книгу Infants and Children in Context - Tara L. Kuther - Страница 199

It is easy to observe that infants grow substantially larger and heavier over time—but there are many individual differences in growth. How can parents and caregivers tell if a child’s growth is normal? By compiling information about the height and weight of large samples of children from diverse populations, researchers have determined that growth follows distinct patterns. Growth norms are expectations for typical gains and variations in height and weight for children based on their chronological age and ethnic background.

In the first few days after birth, newborns shed excess fluid and typically lose 5% to 10% of their body weight. After this initial loss, however, infants gain weight quickly. Infants typically double their birthweight at about 4 months of age, triple it by 12 months, and quadruple it by 2.5 years (Kliegman et al., 2016). The average 3-year-old weighs about 31 pounds. Gains in height of 10 to 12 inches can be expected over the first year of life, making the average 1-year-old child about 30 inches tall. Most children grow about 5 inches during their second year of life and 3 to 4 inches during their third. To parents, growth may appear slow and steady, but research has shown that it tends to occur in spurts in which an infant or toddler can grow up to one-quarter of an inch overnight (Lampl et al., 2001). Infant growth appears to be tied to sleep, as increased bouts of sleep predict small bursts of growth (Lampl & Johnson, 2011). At about 2 years of age, both girls and boys have reached one-half of their adult height (Kliegman et al., 2016).