Infant Growth and Development Milestones

Infant Growth

• Weight: Average infant weighs 3,400g (7.5 lb) at birth. Weight doubles by 4-6 months and triples by 12 months.
• Length: Average length is 50 cm (20 in) at birth, increasing by 50% by 12 months.
• Head Circumference: Average head circumference is 35 cm (13.5 in) at birth, increasing by approximately 10 cm by 12 months.

Assessing Developmental Milestones

• Parent Evaluation: Inquire with the parent about developmental milestones attained.
• Observation: Observe the skill during assessment.
• Screening Tools: Employ screening tools such as:
  • Ages and Stages Questionnaire (ASQ)
  • Infant-Toddler Checklist (ITC)
  • Infant Development Inventory (IDI)
  • Parents' Evaluation of Developmental Status-Developmental Milestones (PEDS-DM).

Physiologic Changes

• Immature Systems: Infant systems are immature at birth, maturing over the first year.
• Neurologic System: The central nervous system (CNS) isn't fully myelinated. Primitive reflexes are present at birth.

Reflexes

• Step: The infant kicks legs when held upright (disappears 4-8 wk).
• Root: Turns head towards a touched or stroked area on the mouth (disappears 3 mos).
• Suck: Disappears (2-5 mos).
• Moro: Startle reflex (disappears 4 mos).
• Asymmetric Tonic Neck: Opposite arm and leg extension (disappears 4 mos).
• Plantar: Toes curl backward when sole of foot is stimulated (disappears 9 mos).
• Palmar Grasp: Grasps fingers introduced to the palm (disappears 4-6 mos).
• Babinski: Toes fan out when sole of foot is stimulated (disappears 12 mos).
• Neck Righting: Turns head when lying on the back (4-6 mos).
• Parachute (Sideways): Reaches out opposite the push to prevent falling sideways (6 mos).
• Parachute (Forward): Reacts to forward rotation while held upright (6-7 mos).
• Protective Reflexes: As primitive reflexes fade, protective reflexes develop for maintaining balance and are present throughout life.

Respiratory System

• Immature Structures: Infant nasal passages are narrower, the larynx is more funnel-shaped, and the trachea and chest wall are more compliant than in adults.
• Less Developed Alveoli: Bronchi, bronchioles and alveoli are also less developed, Fewer in number.
• High Respiratory Rate: Respiratory rate is initially high but decreases with maturity.

Cardiovascular System

• Heart Growth: Heart doubles in size during the first year.
• Pulse Rate: Average pulse rate is 120-140 bpm in newborns, decreasing to approximately 100 bpm by one year.
• Blood Pressure: Average blood pressure is 60/40 in newborns, consistently increasing to 100/50 by 12 months.
• Peripheral Capillaries: Peripheral capillaries are closer to the skin surface, making newborns and young infants more susceptible to heat loss, with improved thermoregulation over the first few months.

Gastrointestinal System

• Tongue Size: Infant tongue is large relative to oral cavity size, aiding in latching.
• Increased Stomach Capacity: Stomach capacity increases with growth.
• Teeth Emergence: First primary teeth (incisors) typically erupt between 6 - 8 months.
• Stool Changes: Stools change from meconium at birth to varying consistencies and frequencies based on feeding.

Genitourinary System

• Frequent Urination: Frequent urination is common.
• Low Specific Gravity: Specific gravity of the urine is lower.
• Reduced Renal Function: All renal functions are less developed compared to adults.
• Dehydration Susceptibility: Infants are more susceptible to dehydration.
• Poor Urine Concentration: Their ability to concentrate urine is less efficient.

Integumentary System

• Newborn Characteristics: Lanugo and vernix may be present at birth. Acrocyanosis is normal in newborns (and fades within days).
• Thin Skin: Infant skin is relatively thinner than adult skin.
• Superficial Capillaries: Peripheral capillaries are more superficial, leading to greater heat loss susceptibility.

Hematopoietic and Immunologic Systems

• High Hemoglobin: High hemoglobin level at birth, decreasing over the first 2-3 months, stabilizing by 6-9 months with adequate iron intake.
• Maternal IgG: Maternal IgG is transmitted to the infant, protecting it in the first 3-6 months of life.

Developmental Theories

• Erikson: Trust vs. Mistrust (birth-1 year). Responding to needs (feeding, diaper changing etc). Infant realizes separateness from parents.
• Piaget: Sensorimotor (birth to 2 years):
  • Stages 1-4: Reflexive behavior, circular reactions, object permanence to more complex interactions. Learning from senses and motor skills.
• Freud: Oral Stage (birth to 1 year): Focus on feeding and sucking.

Social and Emotional Development

• Stranger Anxiety: Develops around 8 months, infant recognizing self as separate.
• Separation Anxiety: Develops later, infant distressed upon parent's leaving.
• Temperament: Ranges from low - moderately active, regular and predictable to highly active, intense, less adaptable.

Gross Motor Skill Progression

• 1 Month: Lifts, turns head when prone, head lag.
• 2 Months: Raises head and chest, improving head control.
• 3 Months: Raises head 45 degrees in prone, slight head lag.
• 4 Months: Lifts head and looks around, rolls from prone to supine.
• 5 Months: Rolls from supine to prone and back, sits upright with support.
• 6 Months: Tripod sits.
• 7 Months: Sits alone with some use of hands.
• 8 Months: Sits unsupported.
• 9 Months: Crawls, abdomen off floor.
• 10 Months: Pulls to stand, cruises.
• 12 Months: Sits from standing position, walks independently.

Fine Motor Skill Progression

• 1 Month: Fists mostly clenched, involuntary hand movements.
• 3 Months: Holds hand in front of face, hands open.
• 4 Months: Bats at objects.
• 5 Months: Grasps rattle.
• 6 Months: Releases object to take another.
• 7 Months: Transfers objects from one hand to the other.
• 8 Months: Gross pincer grasp (rakes).
• 9 Months: Bangs objects together.
• 10 Months: Fine pincer grasp, places and removes objects.
• 11 Months: Offers and releases objects to others.
• 12 Months: Feeds self, makes marks, pokes with index finger.

Premature Infants

• Detail omitted. (Information about premature infants was not fully described in the text.)

Explore key aspects of infant growth, including average weight, length, and head circumference changes in the first year. Assess developmental milestones through parent evaluations and observation, utilizing effective screening tools for comprehensive evaluation.