Infants and Children in Context. Tara L. Kuther

telomeres, protective caps on chromosomes that predict longevity, at age 4 and 5 (Wojcicki et al., 2016).

      Research on the effects of breastfeeding on cognitive development yields mixed findings. In some studies, infants breastfed for more than 6 months perform better on tests of cognitive ability compared with their formula-fed counterparts (Kramer et al., 2008; Sloan, Stewart, & Dunne, 2010). Others suggest that the differences in test scores are influenced by the characteristics of mothers who breastfeed, such as higher levels of education and socioeconomic status (Der, Batty, & Deary, 2006; Schulze & Carlisle, 2010; Tanaka, Kon, Ohkawa, Yoshikawa, & Shimizu, 2009). Yet studies that control for maternal factors still support a cognitive advantage to breastfed infants (Sloan et al., 2010). The cognitive advantages may persist throughout childhood into adolescence. The duration of breastfeeding, specifically longer than 6 months, is associated with higher scores in language ability at ages 5 and 10 (Whitehouse, Robinson, Li, & Oddy, 2011) and intelligence in adolescence (Isaacs et al., 2010). Although breastfeeding appears to be associated with positive cognitive outcomes, it is important to recognize that differences in cognitive development between breastfed and formula-fed infants are small (Jenkins & Foster, 2014; Schulze & Carlisle, 2010).

      Although breastfeeding is recommended by pediatricians, it is not essential for a healthy infant. Many mothers do not breastfeed whether by choice or circumstance. Infant formula is a safe and healthy alternative to breast milk. Formula production is monitored by the U.S. Food and Drug Administration. Most formulas are made from cow’s milk, but soy-based alternatives exist for infants with allergies or parents who choose to raise their child vegetarian.

      Malnutrition

      Many infants experience malnutrition, with devastating effects on physical growth. One in four children in the world suffer from growth stunting, a reduced growth rate. Children in developing countries are at especially high risk of chronic malnutrition and growth stunting. For example, growth stunting affects 43% of children in East African countries, 34% in West Africa, and 35% in South-Central Asia (de Onis & Branca, 2016). Infants who consume a diet that is chronically insufficient in calories, nutrients, and protein can develop marasmus, a wasting disease in which the body’s fat and muscle are depleted (Kliegman et al., 2016). Growth stops, the body wastes away, the skin becomes wrinkly and aged looking, the abdomen shrinks, and the body takes on a hollow appearance. Another disease related to malnutrition is kwashiorkor, found in children who experience an insufficient intake of protein, which may occur when a child prematurely abandons breastfeeding, such as after the birth of a younger sibling. Kwashiorkor is characterized by lethargy, wrinkled skin, and fluid retention appearing as bloating and swelling of the stomach, face, legs, and arms. Because the vital organs of the body take all of the available nutrients, the other parts of the body deteriorate. Marasmus occurs most often in infants, whereas kwashiorkor tends to occur in older infants and young children (Morley, 2016).

      A swollen belly is characteristic of kwashiorkor, an extreme nutritional deficiency.

      Lyle Conrad/CDC

      Malnutrition influences development in multiple ways. Malnourished children show cognitive deficits as well as impairments in motivation, curiosity, language, and the ability to effectively interact with the environment throughout childhood and adolescence and even into adulthood (Galler et al., 2012; C. J. Peter et al., 2016). Malnourishment damages neurons, as shown in Figure 4.3, and the resulting neurological and cognitive deficits from early malnutrition last. For example, among Ghannan children who survived a severe famine in 1983, those who were youngest at the time of the famine (under age 2) scored lower on cognitive measures throughout childhood and into adulthood than did those who were older (ages 6 to 8) (Ampaabeng & Tan, 2013). Malnutrition during the first year of life is associated with depression years later, when those children are 11 to 17 years old (Galler et al., 2010). Some of the damage caused by malnutrition can be reversed. For example, motor and mental development can be enhanced if nutrition is reinstated early. However, long-term difficulties in attention, learning, and intelligence often remain, even into middle adulthood (Kim, Fleisher, & Sun, 2017; Schoenmaker et al., 2015; Waber et al., 2014).

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      Figure 4.3 Effects of Malnourishment on Brain Development

      Source: de Onis and Branca (2016), https://onlinelibrary.wiley.com/doi/epdf/10.1111/mcn.12231 licensed under CC BY 3.0 IGO, https://creativecommons.org/licenses/by/3.0/igo/legalcode

      Although malnutrition is common in developing countries, it is also found in some of the world’s wealthiest countries. Because of socioeconomic factors, many children in the United States and other developed countries are deprived of diets that support healthy growth. In 2017, about 16% of U.S. households with children were categorized as food insecure. That is, they lacked consistent access to food to support a healthy lifestyle for all members of the family at some point during the year (Coleman-Jensen, Rabbitt, Gregory, & Singh, 2018). As shown in Figure 4.4, rates of food insecurity are higher in Black and Hispanic households (22% and 18%, respectively) and those headed by single parents (20% for homes headed by single men and 30% for those headed by single women). In the United States and other developed nations, food insecurity is linked with stunted growth, poor school performance, and health and behavior problems (Shankar, Chung, & Frank, 2017; Zhu, Mangini, Dong, & Forman, 2017).

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      Figure 4.4 Food Insecurity

      Source: Coleman-Jensen et al. (2018).

      Health Threats

      We have seen that poor nutrition and poverty can contribute to poor physical growth. Sometimes developmental difficulties occur despite access to nutrition.

      Growth Faltering

      Although growth follows particular norms, children’s rate of growth varies with hereditary and contextual factors. Some children, however, show significantly slower growth than other children their age. Some infants demonstrate growth faltering, also known as failure to thrive, a condition in which their growth and weight are substantially lower than other children their age. Specifically, growth faltering refers to weight below the fifth percentile for the child’s age, meaning that the child weighs less than 95% of same-age children (Raab, 2017). Their caloric intake is insufficient to maintain growth (Larson-Nath & Biank, 2016). Children with growth faltering may be irritable and emotional, lack age-appropriate social responses such as smiling and eye contact, and show delayed motor development. Untreated, growth faltering is accompanied by delays in cognitive, verbal, and behavioral skills that make it difficult for the child to achieve success in school, home, and peer environments (Homan, 2016).

      Growth faltering may be influenced by medical conditions. Sometimes socioemotional and contextual factors contribute to growth faltering, such as an insecure attachment to caregivers, parents with physical or mental health problems, emotional neglect and abuse, and, especially, living in poverty and experiencing contextual stressors such as violence within the community (Feigelman & Keane, 2017). Pediatricians typically treat growth faltering by providing the child with the nutrients necessary to grow normally. They may also work with other health professionals such as psychologists and social workers to address underlying medical and psychosocial contributors. Although nutritional interventions can alleviate many of the effects of malnutrition on physical development, some children