LIFE D CH-3

Chapter 3: Infancy and Toddlerhood

Overview of Development in Early Years

• Focus on physical, cognitive, and socioemotional development in the first two years of life.

• Significance of early development has been debated; some argue it's overstated (Bruer, 1999).

Overall Physical Growth

• Average newborn in the U.S. weighs ~7.5 pounds (between 5-10 pounds) and is about 20 inches long.

• Initial weight loss of ~5% in days after birth is common and temporary as infants adjust to feeding.

• Growth milestones:

  • By 4 months, weight typically doubles.

  • By 1 year, weight triples.

  • By age 2, weight quadruples (20-40 pounds).

  • Length at 1 year averages ~29.5 inches; by 2 years ~34.4 inches (Bloem, 2007).

Body Proportions

• Dramatic changes in body proportions during early life:

  • Head size accounts for 50% of total length in the womb, 25% at birth, and 20% by age 25.

Learning Objectives

• Summarize overall physical growth.

• Describe brain growth and development in infancy.

• Explain sleep patterns in infants.

• Identify newborn reflexes and compare gross vs. fine motor skills.

• Contrast sensory development in newborns.

• Describe the habituation procedure.

• Discuss breastfeeding benefits and timing for solids.

• Explore nutritional concerns such as marasmus and kwashiorkor.

Page 2: The Brain in the First Two Years

Dramatic Changes in the Brain

• Infants are born with ~85 billion neurons that store and transmit information (Huttenlocher & Dabholkar, 1997).

• Most neurons are immature at birth. Developmental processes include:

  • Dendrites: Branching extensions enhance neuron connections. By age 2, a neuron may have thousands of dendrites.

  • Synaptogenesis: Formation of neuron connections increases rapidly during infancy, referred to as synaptic blooming.

  • Synaptic Pruning: Unused connections are eliminated to enhance efficiency (Webb, Monk, & Nelson, 2001).

Neural Growth Periods

• Blooming occurs early, while pruning continues through childhood and adolescence.

Myelination Developments

• Myelin, a fatty coating around axons, enhances signal transmission and neural pathway building.

• Infant brain weight at birth is about 250 grams; by one year, it grows to 750 grams (Eliot, 1999).

Page 3: Brain Structure and Function

Cortex Structure

• The cortex controls voluntary activity and is divided into two hemispheres with four lobes each:

  • Frontal Lobe: Thinking, planning, memory, and judgment.

  • Parietal Lobe: Processes touch and spatial orientation.

  • Occipital Lobe: Responsible for visual processing.

  • Temporal Lobe: Involved in hearing and language (Jarrett, 2015).

Asymmetrical Development

• Different brain areas mature at different rates; primary motor areas develop before sensory areas.

• Prefrontal cortex, which regulates emotions and complex skills, matures slower (Giedd, 2015).

Page 4: Neuroplasticity and Emotional Regulation

Neuroplasticity

• Capability of the brain to reorganize itself in response to experiences or injury.

• Age significantly influences neuroplasticity, with infants having a higher capacity for changes compared to adults.

Infant Sleep Patterns

• Newborns typically sleep ~16.5 hours per day (polyphasic sleep).

  • By one month, ~15 hours; at 6 months ~14 hours; at 2 years ~10 hours.

• 50% of newborn sleep time is in REM sleep, decreasing to 25-30% in childhood.

Sudden Unexpected Infant Deaths (SUID)

• About 3,500 SUIDs occur annually in infants under one year old (CDC, 2019).

  • Types of SUID include:

    • Sudden Infant Death Syndrome (SIDS): Unexplained death in a healthy infant.

    • Unknown Cause: Lack of investigation leading to undetermined cause.

    • Accidental Suffocation/Strangulation: Common causes include soft bedding or being wedged in objects.

Page 5: SUID Research Findings

Analysis of Bed-Sharing Risks

• Studies show bed-sharing increases SIDS risk, especially in young infants.

• Factors include parental smoking and substance use.

Cultural Contexts of Sleep

• Co-sleeping is prevalent in many collectivist cultures; sleeping arrangements differ (e.g., harder surfaces).

Page 6: Infant Reflexes and Motor Development

Reflexes Overview

• Common Infant Reflexes:

  • Sucking: Responds positively to lips.

  • Rooting: Turns head when cheek is touched.

  • Grasp: Automatically grips anything in palm.

  • Babinski: Toes fan out when foot is stroked.

  • Moro: Arms spread out in response to noise or support loss.

  • Tonic Neck: Fencer pose reflex on head rotation.

Page 7: Motor Development Sequence

Progression of Motor Skills

• Development occurs in a cephalocaudal (head to tail) and proximodistal (center to outward) manner.

• Example milestones include:

  • Holding head up at ~6 weeks.

  • Sitting alone at ~7 months.

  • Walking begins with assistance.

Page 8: Sensory Capacities

Newborn Sensory Abilities

• Vision: Poor at birth, developing clarity by months, with color perception improving by 5 months.

• Hearing: Keen sensitivity; prefers maternal voice and familiar sounds.

Page 9: Further Sensory Development

Hearing and Touch Sensitivity

• Keen sensitivity to sound; can distinguish familiar voices very early.

• Touch: Immediate responses to touch, temperature, and pain; pain sensitivity shown during circumcision.

Taste and Smell Preferences

• Infants can distinguish tastes and show preferences for sweet flavors and maternal scents.

Page 10: Intermodality and Habituation

Intermodal Perception

• Infants exhibit ability to coordinate stimulation from multiple senses effectively at an early age.

Habituation Assessment

• Habituation procedures measure attention and memory skills; slower habituation may indicate developmental delays.

Page 11: Nutrition and Breastfeeding Benefits

Importance of Breastfeeding

• Breast milk, especially colostrum, is vital for nutrition and immunology.

  • Benefits include lower rates of various diseases and infections.

• Recommendations suggest breastfeeding for the first year or two.

Page 12: Introducing Solid Foods

Guidelines for Solid Food Introduction

• Signs of readiness include sitting unassisted and showing interest in foods.

• First solids typically include iron-fortified cereals.

• Avoid choking hazards and assess for allergies carefully.

Page 13: Malnutrition Concerns

Types of Malnutrition

• Marasmus: Severe undernutrition leading to muscle and fat loss.

• Kwashiorkor: Protein deficiency often following breastfeeding cessation.

  • Rates of wasting are still significant in certain regions, particularly in Asia and Africa (UNICEF, 2015).

Long-term Effects

• Malnutrition in early years can have lasting cognitive effects and impact academic performance.