Lifespan Development. Tara L. Kuther

1.13, 6.48

      Puerto Rican: 1.77, 9.40

      Cuban: 1.55, 7.43

      Central and South American: 1.13, 6.67

      Total: 1.42, 7.99

      Part II Infancy and Toddlerhood

       Chapter 4: Physical Development in Infancy and Toddlerhood

       Chapter 5: Cognitive Development in Infancy and Toddlerhood

       Chapter 6: Socioemotional Development in Infancy and Toddlerhood

      The most dramatic developments in the lifespan occur in infancy. In addition to tripling their weight during the first year of life, infants progress through an orderly series of motor milestones that transforms them from newborns unable to lift their heads to babies able to roll over, sit up, crawl, and, at about a year of age, walk.

      As infants practice their motor skills, they explore their environment, build their understanding of phenomena, and adapt to the world around them. Cognitive changes are supported by brain development. A multitude of new connections among brain cells are created and pruned in response to experience. Naturally primed to learn language, infants discriminate speech sounds from birth and progress steadily from gurgles and coos, to speech-like babbling, to first words.

      Warm, sensitive, and responsive interactions with caregivers foster close and secure attachment bonds. Caregivers help infants learn to understand and regulate their emotions. In turn, infants influence their caregivers by smiling, reaching, and crawling to them. Infants’ growing ability to express their thoughts and emotions advances parent–child communication and aids in sustaining a secure emotional base that supports their exploration of the world and their physical, cognitive, and socioemotional development.

      Images: ©iStock.com

      4 Physical Development in Infancy and Toddlerhood

      Tara L. Kuther

      iStock/FatCamera

      “You’re such a big girl!” the pediatric nurse exclaimed as she weighed baby Regina. Regina’s mother marveled at how much her daughter had grown during the first 6 months of her lif—she had more than doubled her weight. Over 6 months, Regina has transformed from a newborn unable to raise her head into a baby who can sit up on her own. Her mother told the nurse, “She seems to like spending time on all fours. Maybe she’s practicing and getting ready to crawl.” The nurse smiled and said, “Start thinking about babyproofing your home because Regina will be crawling before you know it!” In the next few months, Regina will crawl, pull herself up to stand, and eventually walk. Babies grow and change very quickly. In this chapter, we explore the physical changes that occur in a child’s first 2 years of life. These first years are collectively called the developmental stage of infancy and toddlerhood. The term toddler refers to toddling, the unsteady gait of babies who are just learning to walk. During this stage, infants and toddlers experience advances in growth, perceptual capacities, and motor skills that enable them to interact with their world and learn in new ways.

      Learning Objectives

       4.1 Discuss growth and the role of nutrition in development during infancy and toddlerhood.

       4.2 Summarize brain development during infancy and toddlerhood.

       4.3 Compare infants’ early learning capacities for habituation, classical conditioning, operant conditioning, and imitation.

       4.4 Describe infants’ developing sensory abilities.

       4.5 Analyze the roles of maturation and contextual factors in infant and toddler motor development.

      Body Growth and Nutrition in Infants and Toddlers

      Perhaps the most obvious change that infants undergo during the first year of life is very rapid growth. 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. During prenatal development, the internal organs develop before the arms and legs. After birth, the trunk grows before the limbs and the limbs before the hands and feet.

      Growth Norms

      It is easy to observe that infants grow substantially larger and heavier over tim—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 growth norms. 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 birth weight 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 often occurs in spurts in which an infant or toddler can grow up to one quarter of an inch overnight (Lampl, Johnson, & Frongillo, 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).

      Description

      Figure 4.1 Body Proportions Throughout Life

      Source: Huelke (1998).

      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). Good nutrition is critical to healthy growth