Physical Development in Infancy

Session Overview

  • Focus on Chapter 3 of Feldman's textbook.

  • Title: Physical Development in Infancy.

  • Activities: Three videos to be watched:

    • The Brazelton presentation.

    • Motor development in infancy.

    • Newborn reflexes.

Period Defined

  • Infancy and toddlerhood spans from birth to three years of age.

Module One: Physical Development in Infancy

Topics Covered

  • Growth and stability.

  • Motor development.

  • Development of the senses.

Reflective Questions

  • Personal reflection prompted for students:

    • Sleeping arrangements as a baby.

    • Breastfeeding vs. bottle feeding.

    • Introduction to solid foods.

    • Milestones: Rolling over, sitting up, crawling, cruising, walking alone.

    • Favorite toys during infancy.

Growth Patterns and Milestones

  • Growth in Height and Weight:

    • First year of life sees greatest height and weight increase.

    • Five months: Average infant's birth weight doubles to approximately 15 lbs.

    • One year: Weight triples to about 22 lbs.

    • By the second birthday, typically 4 times birth weight.

    • First year: Average growth of almost 12 inches, reaching 30 inches by year one.

    • By age two, average height is around three feet.

  • Body Proportions:

    • Disproportional growth at birth (head = 1/4 of body size).

    • By age two: Head is 1/5 of body length, and by adulthood, it is 1/8.

Principles of Growth

  • Cephalocaudal Principle:

    • Growth direction: head and upper body parts develop before lower body parts.

    • Visual abilities develop in the head area prior to walking.

  • Proximodistal Principle:

    • Growth direction: from the center of the body outward.

    • Trunk develops before limbs (arms and legs).

    • Coordination follows proximal-distal pattern (arms before hands).

Nervous System Development

Components

  • Nervous system comprises the brain and extending nerves.

  • Neurons: Basic cells of the nervous system.

    • Structure includes:

    • Cell body with a nucleus.

    • Dendrites: Receive messages from other cells.

    • Axon: Transmits messages to other neurons.

Neuronal Communication

  • Neurons do not physically touch; they communicate via neurotransmitters through synapses.

  • Infants are born with approximately 100 to 200 billion neurons.

    • Few connections initially present at birth.

Brain Development

  • Billions of new neuronal connections are formed in early life.

  • Synaptic Pruning:

    • Elimination of unused neurons, allowing established neurons to communicate more effectively.

    • Despite neuron loss, remaining neurons grow in size and complexity.

  • Average brain weight triples in the first two years, reaching 75% of adult weight by age two.

Sensitivity and Injury

  • The brain is very sensitive to injury (e.g., Shaken Baby Syndrome).

Sleep Patterns in Infants

General Sleep Details

  • Sleep for newborns averages 16-17 hours per day but varies widely.

  • Sleep typically occurs in 2-hour spurts.

Sudden Infant Death Syndrome (SIDS)

  • SIDS: Leading cause of death in infants under one year.

  • Prevention guidelines from the American Academy of Pediatrics:

    • Infants should sleep on their backs.

    • Consider pacifiers during sleep.

    • Infants should share a room with parents for the first six months.

Hypotheses for SIDS Causes

  • Possible causes include undiagnosed sleep disorders, suffocation, nutritional deficiencies, reflex issues, brainstem abnormalities, and undiagnosed illnesses.

Reflexes in Infants

Definition and Importance

  • Reflexes are unlearned, organized, involuntary responses to stimuli.

    • Serve survival value for infants.

Common Reflexes Examples

  • Swimming Reflex: Babies paddle and kick when placed face down in water.

  • Eye Blink Reflex: Protects eyes from excessive light.

Motor Skill Development

  • Newborns initially show limited movement but gradually gain strength and coordination.

  • Crawling: Typically occurs between 8-10 months.

  • Walking: Begins as early as 9 months, with half of infants walking independently by the end of their first year.

Evaluating Infant Behavior

Neonatal Assessment

  • The Brazelton Neonatal Behavioral Assessment Scale (NBAS):

    • Evaluates infant neurological and behavioral responses.

    • Consists of 27 categories across four behavior aspects:

    • Interactions (alertness, cuddliness).

    • Motor behavior.

    • Physiological control (soothing abilities).

    • Stress responses.

Nutritional Needs

  • Growth is fueled by proper nutrition:

    • Infants need about 50 calories per pound of body weight.

    • Breast milk is ideal; solid foods can be introduced after six months.

    • Malnutrition affects growth and cognitive development.

Consequences of Malnutrition

  • Common in developing countries; can lead to poor growth rates and lower IQ scores in children.

  • Severe malnutrition can cause:

    • Marasmus: Growth halts due to severe protein and calorie deficiency.

    • Kwashiorkor: Stomach and face swelling due to water retention.

Sensory Development

Vision

  • Newborn's distance vision: approx. 20/200 to 20/600 (can only see clearly at 20 feet what adults see at 200-600 feet).

  • By six months: Achieves 20/20 vision.

Depth Perception

  • Ability to perceive depth helps infants avoid hazards.

    • Experiment with a visual cliff (Gibson and Walk study).

Hearing

  • Begins before birth; infants can distinguish varying frequencies post-birth.

  • Sound localization develops by age one.

Smell and Taste

  • Infants can recognize their mothers by smell.

  • Innate preference for sweet tastes; show disgust for bitter.

Pain and Touch Sensitivity

  • Infants experience pain; expressions reflect discomfort.

  • Touch sensitivity develops early, evidenced by reflexes like rooting, which is essential for feeding.