Introduction to Growth

Introduction

Normal Growth Patterns

• Definition: the physical process of increasing in size, mass, or number. In human beings, it’s measured with; weight, height/length, Head circumference.
• Growth is a cornerstone of pediatric care.
• Body tissues and organs grow most rapidly during infancy and adolescence, with these exceptions:
  • Brain growth is most rapid during the first 2 years of life.
  • Head circumference (HC) increases 10 cm in the 1st year, another 2-3cm in the 2nd year, and 5-6 cm throughout the remainder of childhood.
  • Lymphoid tissue volume increases rapidly before puberty and then declines until reaching adult levels.
  • Growth of the reproductive organs is slow until puberty.

Weight

• Average weight at birth = 3.4 kg ( 2.5-4.5)
• Full-term infants weight gain patterns:
  • 1 Double(2x) their birth weight at 4-5 months
  • Triple(3x) their birth weight by 12 months
  • Quadruple(4x) their birth weight by 24 months.
• As children grow older, the weight gain continues at a steady but slower rate, averaging about 2-3 kg per year until adolescence, when growth accelerates again during puberty.
• In a prepubertal child, weight gain of < 1 kg /year is cause for concern.

Important Terminologies on Birth Weight

Calculating the Average Weight at Different Ages

Practice Questions

• What is the estimated average weight for a 7 month old baby?
  • Weight= 0.5*7+4= 7.5 kg.
• What is the estimated average weight for an 8 year old child?
  • Weight= 2*8+8= 24 kg.
• What is the estimated average weight for a 12 year old child?
  • Weight= 3*12+7= 43 kg.

Height/Length

• Average full-term newborn length at birth = 50 cm (45-55 cm).
• Full term infants height/length gain patterns:
  • Birth length (height) increases 50% by1 year of age.
  • Birth length (height) doubles by 4 years of age.
  • Birth length (height) triples by 13 years of age.
• After 4 years of age, average height increase is 2 inches (5cm) per year until adolescence.
• If the increase is less than that in a prepubertal child, it is considered a concerning linear growth pattern that needs further evaluation.

Calculating Midparental height (MPH)

• While environmental, genetic, nutritional, and hormonal elements all affect growth, the most influential factors pertain to a child’s parents.
• Adult heights of both parents,along with their patterns of growth in childhood, influence their child’s growth velocity and ultimate height.
• A child’s final adult height normally falls within 2 standard deviations (SDs) (i.e., 4 inches or 10 cm) above or below the calculated MPH.

Practice Questions

• What is the estimated average adult height for a 12 year old boy, knowing that his father's height is 175 cm, and his mother's height is 165 cm?
  • Answer:
  • Midparental Height for a boy formula = Paternal Height+maternal Height+13)/2
  • Boy’s estimated height= (175+165+13)/2
  • Boys’s estimated height =176.5 cm
• What is the estimated average adult height for an 8 year old female , knowing that her father's height is 180 cm, and her mother’s height is 165 cm?
  • Answer:
  • Midparental Height for a girl formula = Paternal Height+maternal Height-13)/2
  • Girl’s estimated height= (175+165-13)/2
  • Boys’s estimated height =163.5 cm

Head Circumference (HC)

• Average Head Circumference at birth = 34-35 cm.
• The fastest rate of head growth occurs between 0 and 2 months, averaging 0.5 cm/week.
• From birth to 6 months, the HC increases by approximately 9–10 cm (43-44 cm).
• From birth to 1 year, the HC increases by approximately 12–14 cm (46–49 cm).
• By 12 months, the brain has completed half its postnatal growth and is 75% of adult size.

Anterior and Posterior Fontanelles

Early and Delayed Closure of Fontanelles

• Causes of Early Closure (Premature Closure)
  • Primary Craniosynostosis
    • Premature fusion of one or more cranial sutures, leading to abnormal head shapes
  • Secondary Craniosynostosis
    • Genetic Disorders
    • Microcephaly
    • Hyperthyroidism
    • Hypercalcemia
    • Head Injury
• Causes of Delayed Closure
  • Physiological
  • Prematurity
  • Nutritional Deficiency (Rickets, Malnutrition)
  • Endocrine Disorders (Hypopituitarism, Congenital hypothyroidism, Hypophosphatemia)
  • Increase Intracranial Pressure (Hydrocephalus)
  • Genetic Disorders (Down’s syndrome, Achondroplasia, Osteogenesis imperfecta)

Body Mass Index (BMI)

• Body Mass Index (BMI) is a numerical value calculated using a person's weight in kilograms divided by the square of their height in meters (kg/m²).
• In pediatrics, BMI is adjusted for age and sex to account for developmental changes and growth patterns, and it is typically expressed as a percentile on growth charts.