4.4 Influences on Early Physical Growth

4.4 Factors Influencing Early Physical Growth

Early physical growth is a complex process resulting from the interplay of various factors. These include genetic predispositions, nutritional intake, and emotional well-being.

Heredity's Contribution to Physical Growth

Heredity plays a significant role in determining an individual's physical growth, particularly height and the rate of growth, when diet and health are adequate.

  • Evidence from Twin Studies: Identical twins exhibit much greater similarity in body size compared to fraternal twins (Dubois ext{ }et ext{ }al., ext{ }2012). This close resemblance underscores the powerful influence of genetics on physical development.

  • Catch-up Growth: Children and adolescents often demonstrate catch-up growth, meaning they return to their genetically influenced growth path once adverse environmental conditions, such as poor nutrition or illness, improve. However, severe negative environmental impacts can permanently compromise the health of internal organs like the brain, heart, and digestive system.

  • Genetic Influence on Body Weight: Genetic makeup also affects body weight. Studies show that the weights of adopted children correlate more strongly with their biological parents than with their adoptive parents (Kinnunen, ext{ }Pietilainen, ext{ } ext{ }Rissanen, ext{ }2006). This indicates a significant genetic component, though environment, especially nutrition, remains crucial.

Nutrition's Crucial Role in Early Development

Nutrition is especially vital during the first two years of life due to the rapid growth of the baby's brain and body.

  • High Energy Needs: Infants have energy needs at least twice those of an adult on a pound-for-pound basis. Approximately 25% of an infant's total caloric intake is dedicated to growth, with additional calories needed for the proper functioning of rapidly developing organs (Meyer, ext{ }2009).

Breastfeeding Versus Bottle-Feeding

Providing adequate and appropriate nutrition is critical; breastfeeding is ideally suited to an infant's needs in early infancy.

Advantages of Breastfeeding

  • Nutritional and Health Benefits: Breastfeeding offers major nutritional and health advantages compared to bottle-feeding with formula.

  • Survival in Poverty-Stricken Regions: In regions with high poverty, breastfed babies are significantly less likely to be malnourished and are 6 to 14 times more likely to survive their first year of life.

  • World Health Organization Recommendations: The World Health Organization recommends breastfeeding until age 2 years, with solid foods introduced at 6 months. Widespread adoption of these practices could save over 800,000 infant lives annually (World ext{ }Health ext{ }Organization, ext{ }2015f).

  • Protection Against Infections: Even a few weeks of breastfeeding provides protection against respiratory and intestinal infections, which are particularly devastating for young children in developing countries.

  • Sibling Spacing: Breastfeeding can help increase the spacing between siblings by reducing the likelihood of a nursing mother becoming pregnant, which is a major factor in reducing infant and childhood deaths in impoverished nations (Note: Breastfeeding is not a reliable method of birth control).

Global Breastfeeding Practices

  • Developing Countries: In Africa, the Middle East, and Latin America, fewer than 40% of babies are exclusively breastfed for the first six months, and one-third are fully weaned before age 1 (UNICEF, ext{ }2015). Many mothers substitute breast milk with commercial formula or low-grade nutrients (e.g., rice water, diluted cow/goat milk), which often lead to illness and death due to contamination from poor sanitation.

  • Promotional Efforts: The United Nations has encouraged hospitals in developing countries to promote breastfeeding, provided mothers do not have transmissible viral or bacterial infections (e.g., HIV, tuberculosis). Most developing countries have banned free or subsidized formula distribution to new mothers.

  • Industrialized Nations: Breastfeeding has become more common, especially among well-educated women, partly due to the natural childbirth movement. In America, 79% of mothers initiate breastfeeding, but about half stop by 6 months (Centers ext{ }for ext{ }Disease ext{ }Control ext{ }and ext{ }Prevention, ext{ }2014a). Early return to work is a factor in earlier weaning (Smith ext{ } ext{ }Forrester, ext{ }2013). Combining breast- and bottle-feeding is an option for mothers who cannot always be with their infants. The U.S. Department of Health and Human Services (2011) advises exclusive breastfeeding for the first 6 months and continued inclusion of breast milk until at least 1 year.

Psychological and Cognitive Outcomes of Breastfeeding

  • Mother-Infant Relationship/Emotional Adjustment: In industrialized nations, breastfed and bottle-fed infants do not differ in the quality of the mother–infant relationship or in later emotional adjustment (Jansen, ext{ }de ext{ }Weerth, ext{ } ext{ }Riksen-Walraven, ext{ }2008;
    Lind ext{ }et ext{ }al., ext{ }2014).

  • Intelligence: Some studies suggest a slight intelligence advantage for breastfed children and adolescents, after controlling for maternal intelligence, SES, and other factors (Belfort ext{ }et ext{ }al., ext{ }2013; Kanazawa, ext{ }2015). However, other studies find no cognitive benefits (Walfisch ext{ }et ext{ }al., ext{ }2013).

Chubby Babies and Later Overweight and Obesity Risk

While most chubby babies tend to thin out during toddlerhood as activity increases and weight gain slows, there is a growing concern regarding rapid weight gain in infancy.

  • Risk Factors: Recent evidence indicates a strengthening relationship between rapid weight gain in infancy and later obesity (Druet ext{ }et ext{ }al., ext{ }2012). This trend may be linked to the rise in adult overweight and obesity, leading parents to promote unhealthy eating habits in their young children.

    • Dietary Habits: Interviews with U.S. parents of 4- to 24-month-olds revealed that many routinely served French fries, pizza, candy, sugary fruit drinks, and soda. Infants consumed 20% and toddlers 30% more calories than needed, while as many as one-fourth ate no fruits and one-third no vegetables (Siega-Riz ext{ }et ext{ }al., ext{ }2010).

  • Prevention Strategies: Parents can take several steps to prevent infants from becoming overweight children and adults:

    • Exclusive Breastfeeding: Exclusively breastfeeding for the first six months is associated with slower weight gain in the first year, a leaner body build through early childhood, and a 10% to 20% reduced risk of obesity in later life

    • Healthy Food Choices: Avoid giving babies foods high in sugar, salt, and saturated fats.

    • Energetic Play: Once toddlers are mobile, provide ample opportunities for active play.

    • Limit Screen Time: Reduce the time very young children spend watching television, as excessive viewing correlates with overweight in older children.

Malnutrition

  • Prevalence and Impact: Malnutrition is widespread in developing countries and war-torn areas, contributing to one-third of worldwide infant and early childhood deaths (approximately 2.12.1 million children annually). It is also responsible for growth stunting in nearly one-third of the world’s children under age 55 (WorldextHealthextOrganization,ext2015cWorldextHealthextOrganization,ext2015c).

  • Types of Malnutrition Diseases: The 8% of children severely affected suffer from two primary dietary diseases:

    • Marasmus: A wasted condition of the body caused by a diet low in all essential nutrients.

      • It usually appears in the first year of life when a baby’s mother is too malnourished to produce enough breast milk, and bottle-feeding is also inadequate.

      • The starving baby becomes painfully thin and is at high risk of death.

    • Kwashiorkor: Caused by an unbalanced diet very low in protein.

      • The disease usually strikes after weaning, between 11 and 33 years of age.

      • It is common in regions where children consume enough calories from starchy foods but little protein.

      • The child’s body responds by breaking down its own protein reserves, leading to symptoms like an enlarged belly, swollen feet, hair loss, a rash, irritability, and listlessness.

  • Long-Term Consequences: Children who survive these extreme forms of malnutrition often suffer from lasting damage to the brain, heart, liver, pancreas, and other organs (Müller ext{ } & ext{ }Krawinkel, ext{ }2005; Spoelstraextetextal.,ext2012Spoelstraextetextal.,ext2012).

    • When their diets improve, they tend to gain excessive weight (Blackextetextal.,ext2013Blackextetextal.,ext2013) due to a low basal metabolism rate established during malnutrition, which may endure. Malnutrition may also disrupt appetite control centers in the brain, causing children to overeat when food becomes plentiful.

  • Impacts on Learning and Behavior:

    • Animal evidence reveals that a deficient diet permanently reduces brain weight and alters the production of neurotransmitters in the brain, which can disrupt all aspects of development (Haller,ext2005Haller,ext2005).

    • Children who experienced marasmus or kwashiorkor show poor fine-motor coordination, have difficulty paying attention, often display conduct problems, and score low on intelligence tests into adulthood

    • They may also display a more intense stress response to fear-arousing situations, possibly caused by the constant pain of hunger (Fernald ext{ } & ext{ }Grantham-McGregor, ext{ }1998).

    • Irritability and passivity in malnourished children can compound the developmental consequences of poor diet, even with mild to moderate nutritional deprivation.

  • Food Insecurity in Developed Nations (U.S. example):

    • An estimated 19% of U.S. children suffer from food insecurity (uncertain access to enough food for a healthy, active life).

    • Food insecurity is especially high among single-parent families (35%) and low-income ethnic minority families (e.g., African Americans 26%, Hispanics 22%) (U.S.extDepartmentextofextAgriculture,ext2015aU.S.extDepartmentextofextAgriculture,ext2015a).

    • Although few of these children experience marasmus or kwashiorkor, their physical growth and ability to learn are still negatively affected.