Читать книгу Infants and Children in Context - Tara L. Kuther - Страница 200

Over the course of infancy, children get larger and heavier, but growth is uneven. Different parts of the body grow at different rates. Growth during the prenatal period and infancy proceeds in two systematic patterns. Cephalocaudal development refers to the principle that growth proceeds from the head downward. The head and upper regions of the body develop before the lower regions. For example, recall the fetus’s disproportionately large head. During prenatal development, the head grows before the other body parts. Even at birth, the newborn’s head is about one-fourth the total body length, as shown in Figure 4.1. As the lower parts of the body develop, the head becomes more proportionate to the body. By 3 years of age, the child is less top-heavy. Proximodistal development refers to the principle that growth and development proceed from the center of the body outward (Figure 4.2). During prenatal development, the internal organs develop before the arms and legs. After birth, the trunk grows ahead of the arms and legs, and the arms and legs tend to grow ahead of the hands and feet.

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Figure 4.1 Body Proportions Throughout Life

Source: Huelke (1998).

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Figure 4.2 Cephalocaudal and Proximodistal Development

Growth is largely maturational, but it can be influenced by health and environmental factors. Today’s children grow taller and faster than ever before, and the average adult is taller today than a century ago. Increases in children’s growth over the past century are influenced by contextual changes such as improved sanitation, nutrition, and access to medical care (Mummert, Schoen, & Lampl, 2018). Large gains have occurred in North America and Europe, followed by South Asia (NCD Risk Factor Collaboration, 2016). Although children of sub-Saharan Africa showed growth gains into the mid-1990s, mass poverty and starvation, poor infrastructure to provide clean water and sanitation, and exposure to the emotional and physical stresses of war and terror have affected growth (Simmons, 2015). Contextual factors can both help and harm children’s development.