Lifespan Development. Tara L. Kuther

infants’ first nutritional experiences are through breastmilk or formula.

      Breastfeeding

      The U.S. Department of Health and Human Services (2011) has recommended that mothers breastfeed their babies, and breastfeeding has increased in popularity in the United States in recent years. In 1990, about one half of mothers breastfed their babies, while about 83% breastfed in 2014 (Centers for Disease Control and Prevention, 2017). Over one half of women continue to breastfeed after 6 months and over one third at 12 months.

      Breastfeeding practices vary by maternal age, education, and socioeconomic status (Hauck, Fenwick, Dhaliwal, & Butt, 2011). In the United States and the United Kingdom, for example, the lowest rates of breastfeeding are among low-income mothers, mothers who are young, and mothers with low levels of education. Researchers have observed that the employment settings of low-income mothers may offer few resources to support breastfeeding, such as private places for women to use breast pumps (Griffiths, Tate, & Lucy, 2007; Racine, Frick, Guthrie, & Strobino, 2009). In contrast, women in developing countries who have low educational levels and are in the poorest social classes are more likely to breastfeed their children. Educated women of higher income brackets in these countries tend to shun breastfeeding, viewing it as an option primarily for poor women (Victora et al., 2016). Other factors affecting breastfeeding practices include ethnicity and social policies. In the United States, for instance, Hispanic mothers breastfeed at higher rates than non-Hispanic White mothers, who are more likely to breastfeed than non-Hispanic Black mothers (Centers for Disease Control and Prevention, 2013; Smith-Gagen, Hollen, Walker, Cook, & Yang, 2014). And unsurprisingly, countries where working women are allowed paid maternity leave for part or all of their infant’s first year of life, such as Denmark, Norway, Sweden, and Australia, show very high breastfeeding rates of 94% and more (Hauck et al., 2011; Imdad, Yakoob, & Bhutta, 2011; Roelants, Hauspie, & Hoppenbrouwers, 2010).

      Breast-feeding is associated with many health benefits for infants and mothers, and provides opportunities for infant–mother bonding.

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      Breastfeeding offers benefits for mothers and infants. Mothers who breastfeed have lower rates of diabetes, cardiovascular disease, and depression, and after they reach menopause, they are at lower risk for ovarian and breast cancer and bone fractures (Godfrey & Lawrence, 2010; Islami et al., 2015). A mother’s milk is tailored to her infant and has the right amount of fat, sugar, water, and protein needed for the baby’s growth and development. Most babies find it easier to digest breast milk than formula. In addition, breast milk contains immunizing agents that protect the infant against infections, and breastfed infants tend to experience lower rates of allergies and gastrointestinal symptoms as well as have fewer visits to physicians (Cabinian et al., 2016; Turfkruyer & Verhasselt, 2015). Breastfeeding for more than 6 months is associated with reduced risk of obesity and childhood cancer, especially lymphomas (Amitay, Dubnov Raz, & Keinan-Boker, 2016; Victora et al., 2016). Recent research suggests that exclusively breastfeeding during the first 4 to 6 weeks of life may be associated with longer 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).

      Despite these benefits, many mothers choose not to breastfeed or are unable to breastfeed. Infant formula is a safe and healthy alternative to breast milk. While breastfeeding is recommended by pediatricians, formula feeding will not harm a baby. 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. Infants subsist on milk or formula alone for the first few months of life, after which other foods begin to be integrated into their diet.

      Solid Food

      Somewhere between 4 and 6 months of age, infants eat their first solid food—although “solid food” is actually a misnomer. The first food consumed is usually iron-fortified baby cereal mixed with breast milk or formula to make a very thin gruel. As babies get older, the amount of milk is reduced to make porridge of a thicker consistency. Now infants’ diets begin to include other pureed foods, such as vegetables and fruits. The addition of pureed meats comes later. Infants do not necessarily like these new flavors and textures—many foods must be introduced over a dozen times before an infant will accept them.

      Sometimes babies gain weight quickly and may appear chubby. Parents who feed their infants nutritious foods need not worry about increases in weight and should not restrict infants’ caloric intake without consulting a pediatrician. Most chubby babies become thinner toddlers and young children as they learn to crawl, walk, run, and become more active. In addition, as infants’ get better at manipulating their fingers (as discussed later in this chapter), they begin to feed themselves, which means meals may take more time and may reduce toddlers’ food consumption.

      However, many infants are not served nutritious foods. One recent study of 6- to 24-month-olds found that many were served fattening “junk” foods such as French fries, pizza, candy, and soda, and 20% of the infants had never consumed vegetables (Miles & Siega-Riz, 2017). Most infants are introduced to sweets early, and by 24 months, nearly two thirds consume cookies or candy in a given day (Deming et al., 2017). Rapid, excessive weight gain in infancy is associated with childhood obesity (Wang et al., 2016). Pediatricians suggest that parents consider their infants’ growth in light of norms to determine whether intervention is needed. As shown in Figure 4.2, about 5% of 12-month-old boys and girls weigh 26 pounds or more and are classified as obese (World Health Organization, 2009).

      Figure 4.2 Weight Norms for Infants and Toddlers

      Source: Centers for Disease Control and Prevention, 2009.

      Malnutrition

      Receiving adequate calories and nutrition is a challenge for many children, especially those in developing countries where chronic malnutrition is common. Malnutrition has devastating effects on physical growth, resulting in growth stunting. One in four children in the world suffer from growth stunting, the majority of whom live in developing countries. 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