Biological Growth and Physical Development

  • Biological Growth and Physical Development
    • External proportions
    • Biologic determinants of growth and development
Age Group Weight Height
Birth to 6 months of age Weekly gain: 140 to 200 g (5 to 7 oz) 

Birth weight doubles by end of first 4 to 7 months

Monthly gain: 2.5 cm (1 inch) 
6 to 12 months of age Weight gain: 85 to 140 g (3 to 5 ounces)

Birth weight triples by end of first year

Monthly gain: 1.25 cm (0.5 inch)

Birth length increases by ≈50% by end of first year

Toddlers Birth weight quadruples by age equation.pdf years Height at 2 years of age is ≈50% of eventual adult height

Gain during second year: About 12 cm (4.7 inches)

Gain during third year: About 6 to 8 cm (2.4 to 3.1 inches)

Preschoolers  Yearly gain: 2 to 3 kg (4.5 to 6.5 pounds) Birth length doubles by 4 years of age

Yearly gain: 5 to 7.5 cm (2 to 3 inches)

School-age children Yearly gain: 2 to 3 kg (4.5 to 6.5 pounds) Yearly gain after 7 years: 5 cm (2 inches)

Birth length triples by about 13 years of age

Pubertal Growth Spurt
Females: 10 to 14 years of age Weight gain: 7 to 25 kg (15.5 to 55 pounds)

Mean: 17.5 kg (38.5 pounds)

Height gain: 5 to 25 cm (2 to 10 inches); ≈95% of mature height achieved by onset of menarche or skeletal age of 13 years of age

Mean: 20.5 cm (8 inches)

Males: 11 to 16 years of age Weight gain: 7 to 30 kg (15.5 to 66 pounds)

Mean: 23.7 kg (52.2 pounds)

Height gain: 10 to 30 cm (4 to 12 inches); ≈95% of mature height achieved by skeletal age of 15 years of age

Mean: 27.5 cm (11 inches)

      • Double the height at 2 years of age to estimate how tall he or she may be as an adult
    • Skeletal growth and maturation
      • Factors that may influence skeletal muscle injury rates and types in children and adolescents
        • Less protective sports equipment for children
        • Less emphasis on conditioning, especially flexibility
        • In adolescents, fractures that are more common than ligamentous ruptures because of the rapid growth rate of the physeal (segment of tubular bone that is concerned mainly with growth) zone of hypertrophy
    • Neurologic maturation
      • In contrast to other body tissues, which grow rapidly after birth, the nervous system grows proportionately more rapidly before birth
    • Lymphoid tissue
      • At about 10 to 12 years of age, they reach a maximum development that is approximately twice their adult size but is followed by rapid decline to stable adult dimensions by the end of adolescence


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