Infancy

Fundamental Concepts of Growth and Development

  • Definition of Growth: An increase in the physical size of the whole body or any of its constituent parts. It is quantitative and measured in units such as kg\text{kg}, lbs\text{lbs}, inches\text{inches}, and cm\text{cm}. Physical growth is typically associated with Chronological Age.

  • Definition of Development: A continuous, orderly series of conditions that lead to activities, new motives for activities, and eventual patterns of behavior. It is qualitative and measured through observations of milestones. This is associated with Developmental Age.

  • Importance of Study (Anticipatory Guidance):

    • Knowing what to expect at various age groups serves as a guide for teaching parents about health habits, nutrition, dental care, and sexuality.

    • It assists in illness and injury prevention.

    • It helps health professionals "catch" children who may be falling behind (early intervention).

    • It aids in formulating specific plans of care and understanding the reasoning behind certain illnesses.

    • It enhances social development, family/community relationships, and academic/vocational achievement.

  • Teachable Moments: By understanding developmental stages, parents can use everyday life to enhance language development, intellectual growth, social skills, and motor skills.

Principles and Patterns of Development

  • Directional Trends:

    • Cephalocaudal: Growth and development proceed from the head down toward the tail/feet.

    • Proximodistal: Development proceeds from the center of the body outward toward the extremities.

    • Differentiation: Development moves from simple, gross movements to more complex, refined, and specialized tasks.

  • Predictability and Variation:

    • Patterns are generally predictable and universal to all humans.

    • However, individual differences exist in the timing and rate of development.

  • Sequential Trends: Development follows a specific order (e.g., a child sits before they stand).

  • Phases and Influences:

    • Critical Periods: Specific timeframes where the individual is most sensitive to the presence or absence of certain stimuli.

    • Positive and Negative Stimuli: Environmental factors that can either promote or hinder optimal development.

  • Factors Influencing Development:

    • Genetics

    • Nutrition

    • Prenatal and Environmental Factors

    • Family and Community

    • Cultural Factors

  • Bodily Proportions: Bodily proportions change significantly with age, progressing from a fetus at 2 months2\,\text{months} through birth, 2 years2\,\text{years}, 6 years6\,\text{years}, and finally adulthood at 25 years25\,\text{years}.

Theoretical Frameworks for Development

  • Erikson (Psychosocial Development):

    • Infancy: Trust vs. Mistrust. The infant is entirely dependent on caregivers; quality of care shapes personality. Infants have low tolerance for frustration.

    • Early Childhood: Autonomy vs. Shame and Doubt.

    • Preschool: Initiative vs. Guilt.

    • School Age: Industry vs. Inferiority.

    • Adolescence: Identity vs. Role Confusion.

  • Piaget (Cognitive Development):

    • Intelligence takes the form of motor actions and sensory exploration.

    • Sensorimotor Stages:

      • Reflexive: (Birth to 1 month1\,\text{month}).

      • Primary Circular Reactions: (1−4 months1-4\,\text{months}).

      • Secondary Circular Reactions: (4−8 months4-8\,\text{months}).

      • Coordination of Secondary Reactions: (9−12 months9-12\,\text{months}).

    • Key Transitions: Progression from simple reflexes to repetitive acts; learning they are separate from objects; developing Object Permanence; beginning to use symbols.

  • Kohlberg (Moral Development):

    • Preconventional Morality: Obedience and Punishment Orientation. Children see morality as external rules handed down by powerful authorities that must be obeyed unquestioningly.

    • Conventional Morality.

    • Postconventional Morality.

Chronological Stages of Development

  • Prenatal Period:

    • Germinal: Conception to 2 weeks2\,\text{weeks}.

    • Embryonic: 2 weeks2\,\text{weeks} to 8 weeks8\,\text{weeks}.

    • Fetal: 8 weeks8\,\text{weeks} to 40 weeks40\,\text{weeks} (birth).

  • Infancy:

    • Neonatal: Birth to 28 days28\,\text{days}.

    • Infancy: 1 month1\,\text{month} to 12 months12\,\text{months}.

  • Early Childhood:

    • Toddler: 11 to 2 years2\,\text{years}.

    • Preschooler: 33 to 6 years6\,\text{years}.

  • Middle Childhood:

    • School Age: 66 to 12 years12\,\text{years}.

  • Late Childhood and Adolescence:

    • Prepubertal: 1010 to 12 years12\,\text{years}.

    • Adolescence: 1313 to 18 years18\,\text{years}.

Biological Growth in Infancy (0−1 Year0-1\,\text{Year})

  • Weight Parameters:

    • Infants lose 5 %5\,\% to 10 %10\,\% of their initial birth weight within the first 3−4 days3-4\,\text{days} due to hormone withdrawal from the mother, loss of extracellular fluid, passage of meconium and urine, and limited initial food intake.

    • Gains: Weight increases by approximately 1 oz/day1\,\text{oz}/\text{day} for the first 6 months6\,\text{months}.

    • Milestones: Birth weight doubles by 6 months6\,\text{months} and triples by 1 year1\,\text{year}.

  • Height/Length Parameters:

    • Increases by 1 inch/month1\,\text{inch}/\text{month} until 6 months6\,\text{months}.

    • Total height increases by 50 %50\,\% by the end of 1 year1\,\text{year}.

  • Head Circumference:

    • Increases by 0.5 inches/month0.5\,\text{inches}/\text{month} for the first 6 months6\,\text{months}.

    • Skull features include the Anterior Fontanelle, Posterior Fontanelle, Sagittal Suture, Metopic Suture, Coronal Suture, and Lambdoid Suture.

  • Stomach Capacity Progression:

    • Day One: Size of a cherry (5−7 ml5-7\,\text{ml} or 1−1.4 teaspoons1-1.4\,\text{teaspoons}).

    • Day Three: Size of a walnut (22−27 ml22-27\,\text{ml} or 0.75−1 oz0.75-1\,\text{oz}).

    • One Week: Size of an apricot (45−60 ml45-60\,\text{ml} or 1.5−2 oz1.5-2\,\text{oz}).

    • One Month: Size of a large egg (80−150 ml80-150\,\text{ml} or 2.5−5 oz2.5-5\,\text{oz}).

Maturation of Physiological Systems in Infancy

  • Respiratory System:

    • Infants are abdominal breathers.

    • Rate slows from a newborn average of 30−60/min30-60/\text{min} (average 40/min40/\text{min}) to 20−30/min20-30/\text{min} by 1 year1\,\text{year}.

  • Cardiovascular System:

    • Heart rate slows: Newborn (120−160 bpm120-160\,\text{bpm}; 100 bpm100\,\text{bpm} when sleeping, 160 bpm160\,\text{bpm} when crying) to 100−120 bpm100-120\,\text{bpm} by 1 year1\,\text{year}.

    • Paradoxical pattern present (rate increases with inspiration, decreases with expiration).

    • Blood Pressure: At birth, average is 75/42 mm Hg75/42\,\text{mm Hg} (Systolic 60−8060-80, Diastolic 40−5040-50). By 1 year1\,\text{year}, it rises to approximately 100/60 mm Hg100/60\,\text{mm Hg}.

  • Temperature Regulation:

    • Rectal: 90.0∘F90.0^\circ\text{F} to 99.5∘F99.5^\circ\text{F} (35.6∘C35.6^\circ\text{C} to 37.5∘C37.5^\circ\text{C}).

    • Axillary: 97.6∘F97.6^\circ\text{F} to 98.6∘F98.6^\circ\text{F} (36.5∘C36.5^\circ\text{C} to 37.0∘C37.0^\circ\text{C}).

    • Thermoregulation improves as adipose tissue develops; shivers by few months; adjusts to cold by 6 months6\,\text{months}.

  • Hemopoietic System:

    • Fetal hemoglobin is present for the first 5 months5\,\text{months} (shorter RBC lifespan), leading to potential physiologic anemia.

    • Maternal iron stores diminish at 5−6 months5-6\,\text{months}.

  • Digestive System:

    • Immature at birth; functions fully around 3 months3\,\text{months}. Drooling occurs due to poorly coordinated swallowing.

    • Enzymes: Amylase (carbohydrates) and lipase (fats) function at 4−6 months4-6\,\text{months}.

    • Solid foods are better tolerated around 4−6 months4-6\,\text{months} coincident with teeth eruption and coordination of sucking/swallowing.

  • Renal and Fluids:

    • Immature kidneys; cannot concentrate urine well.

    • Total body water is 75 %75\,\% at birth (primarily extracellular fluid), making infants highly prone to severe dehydration.

  • Endocrine System: Immature functioning makes infants vulnerable to imbalances in glucose, amino acids, electrolytes, and stress.

Sensory and Motor Development Milestones

  • Vision:

    • Birth to 1 M1\,\text{M}: Follows objects to midline; sees 8−10 inches8-10\,\text{inches} away.

    • 2 M2\,\text{M}: Lift and look.

    • 3 M3\,\text{M}: Interest in faces; begins associating visual stimuli and events.

    • 4 M4\,\text{M}: Hand regard; follows past midline; recognizes familiar objects and parents.

    • 6 M6\,\text{M}: Directed reach; development of depth perception.

    • 10 M10\,\text{M}: Achievement of Object Permanence.

    • 12 M12\,\text{M}: Able to follow objects well.

  • Hearing and Taste:

    • Discrimination of mother’s voice at birth.

    • 3−6 M3-6\,\text{M}: Localizes sound; understands a few words.

    • 6 M6\,\text{M}: Taste preferences (accepts sweet, resists bitter/sour).

    • 7 M7\,\text{M}: Responds to own name.

    • 12 M12\,\text{M}: Follows simple commands.

  • Dentition: First deciduous tooth erupts by 5−6 months5-6\,\text{months} (usually lower central incisor).

  • Gross Motor Milestones:

    • Head Control: Marked lag at birth to 1 M1\,\text{M}. Sits with support by 4 M4\,\text{M}. Established control by 4−6 M4-6\,\text{M}.

    • Rolling: Belly to back by 5 M5\,\text{M}; back to belly by 6 M6\,\text{M}.

    • Sitting: Needs support at 6 M6\,\text{M}. Sits alone leaning on hands by 7 M7\,\text{M}. Sits unsupported by 8 M8\,\text{M}. Prone-to-sit independently by 10 M10\,\text{M}.

    • Locomotion: Pushes backward at 4−6 M4-6\,\text{M}. Bears all weight on legs by 6−7 M6-7\,\text{M}. Crawls on belly at 8−10 M8-10\,\text{M}. Creeps on hands and knees at 11 M11\,\text{M}.

    • Walking: Stands holding furniture at 9 M9\,\text{M}. Cruises at 10−12 M10-12\,\text{M}. Walks with one hand held at 12 M12\,\text{M}. Takes independent steps shortly after.

  • Fine Motor Milestones:

    • 1 M1\,\text{M}: Hands predominantly closed.

    • 3 M3\,\text{M}: Hands to midline; voluntary grasp begins.

    • 5 M5\,\text{M}: Two-handed voluntary grasp.

    • 4−6 M4-6\,\text{M}: Intentionally brings things to mouth.

    • 6 M6\,\text{M}: Holds bottle; grasps feet.

    • 7 M7\,\text{M}: Transfers objects hand-to-hand.

    • 8−9 M8-9\,\text{M}: Pincer grasp begins (refined by 11−12 M11-12\,\text{M}).

Social and Emotional Development

  • Social Interactions:

    • 1 week1\,\text{week}: Preference for human faces.

    • 6−8 weeks6-8\,\text{weeks}: Social Smile.

    • 3 M3\,\text{M}: Shows excitement at new things.

    • 6 M6\,\text{M}: Very personable and interactive.

    • 7 M7\,\text{M}: Imitates actions and noises; shows displeasure.

    • 10 M10\,\text{M}: Plays games like pat-a-cake and peekaboo.

    • 12 M12\,\text{M}: Highly interactive; shows pleasure and displeasure.

  • Attachment and Separation:

    • Parent-infant attachment is critical to mental health.

    • Stranger Fear/Anxiety: Typically appears as object permanence develops.

    • Separation Anxiety: Occurs in three stages: 1. Protest, 2. Despair, 3. Detachment.

    • Reactive Attachment Disorder (RAD): Results from maladaptive or absent attachment. Symptoms include poor impulse control, refusing eye contact, and potential antisocial behavior. Intervention requires warm, responsive interaction.

  • Emotional Development:

    • Emotions are unstable and change rapidly from crying to laughter.

    • 10 M10\,\text{M}: Anger, sadness, jealousy, and affection are recognizable.

    • 12 M12\,\text{M}: Emotions are clearly distinguishable.

  • Stress and Coping in Infants: Triggers include loss of caregivers, loud noises, bright lights, and sudden movements.

Language, Play, and Temperament

  • Language Development:

    • Crying: Initial communication. Peaks at 2−4 hours/day2-4\,\text{hours}/\text{day} at 6 weeks6\,\text{weeks}, then decreases. Specific cries for specific needs by 1 year1\,\text{year}.

    • Vocalization timeline:

      • 5−6 weeks5-6\,\text{weeks}: Vocalization begins.

      • 2\,&\text{month}: Coos.

      • 3−4 months3-4\,\text{months}: Consonant sounds; laughs aloud.

      • 5−7 months5-7\,\text{months}: Vowel sounds.

      • 8 months8\,\text{months}: Imitates sounds; combines syllables.

      • 12 months12\,\text{months}: Says 3−5 words3-5\,\text{words} with meaning (besides "mama" and "dada").

    • Hearing Health: Ability to hear correlates with proper enunciation. Assess for Otitis Media or fluid in ears (effusion).

  • Play:

    • 0-3 Months: Not differentiated; characterized by smiling and squealing.

    • 3-6 Months: Solitary play. Focus on sensory stimulation (talking, singing, reading). The quality of the interaction is more important than the toy.

    • 7-12 Months: Focus on security, gross/fine motor stimulation, casing relationships, and object permanence. Interactive games (peekaboo).

  • Temperament Patterns:

    • The Easy Child: Generally positive, predictable, and adaptable.

    • The Slow-to-Warm-Up Child: Needs time to adjust to new situations.

    • The Difficult Child: Irregular habits, intense reactions, and slower adjustment.

  • Infant Sleep: 16−20 hours/day16-20\,\text{hours}/\text{day} for the first 4 months4\,\text{months}. By 5 months5\,\text{months}, usually sleep through the night with 22 naps.

Clinical Guidelines and Red Flags

  • Red Flags in Development:

    • Unable to sit alone by age 9 months9\,\text{months}.

    • Unable to transfer objects from hand to hand by age 1 year1\,\text{year}.

    • Abnormal pincer grip or grasp by age 15 months15\,\text{months}.

    • Unable to walk alone by 18 months18\,\text{months}.

    • Failure to speak recognizable words by 2 years2\,\text{years}.

  • Discipline and Setting Limits:

    • Initiate between 6−18 months6-18\,\text{months} to ensure safety.

    • Use a stern "No," maintain negative eye contact, use gestures, and remove the child from unsafe situations.

  • Spoiled Child Syndrome: Distinct from normal toddler negativism or stress; requires consistent, clear guidelines.

Questions & Discussion

  • Q: Why is an infant more prone to dehydration from illness?

    • A: Infants have a high proportion of total body fluid (75 %75\,\% water), mostly in the extracellular fluid compartment, and immature kidneys that cannot concentrate urine.

  • Q: At what age should an infant sit securely without support?

    • A: 8 months8\,\text{months}.

  • Q: At what age should an infant be able to pick up small objects using pincer grasp?

    • A: Development begins at 8−9 months8-9\,\text{months} and is refined by 11−12 months11-12\,\text{months}.

  • Q: At what age do infants focus and follow objects with their eyes? What does this indicate?

    • A: At birth they follow to midline; by 4 months4\,\text{months} they follow past midline. This indicates visual maturation and neurological development.

  • Q: At what age do infants demonstrate a social smile and what is the trigger?

    • A: 6−8 weeks6-8\,\text{weeks}, usually triggered by seeing a human face or hearing a voice.

  • Q: When does an infant typically exhibit stranger anxiety?

    • A: Around the time they develop object permanence (10 months10\,\text{months}).

  • Q: When would an infant be ready for peek-a-boo? Why? What toys promote this?

    • A: Around 10 months10\,\text{months} because of the development of object permanence. Toys that can be hidden and revealed promote this.

  • Q: A 3-month-old child is hospitalized for several months. What steps can the nurse take to foster trust?

    • A: Based on Erikson, providing consistent, responsive care and meeting the infant's needs promptly will foster a sense of trust.

  • Q: How many words should a 12-month-old use?

    • A: 33 to 5 words5\,\text{words} with meaning.

  • Q: A newborn weighs 9 lbs9\,\text{lbs} at birth. What is the expected weight at 6 M6\,\text{M} and 12 M12\,\text{M}?

    • A: 18 lbs18\,\text{lbs} at 6 months6\,\text{months} (double) and 27 lbs27\,\text{lbs} at 12 months12\,\text{months} (triple).

  • Q: A newborn’s length is 22 inches22\,\text{inches} at birth. What is the expected length at 6 M6\,\text{M} and 12 M12\,\text{M}?

    • A: At 6 months6\,\text{months}, length increases by 1 inch1\,\text{inch} per month (22+6=28 inches22 + 6 = 28\,\text{inches}). At 12 months12\,\text{months}, length should increase by 50 %50\,\% (22×1.5=33 inches22 \times 1.5 = 33\,\text{inches}).