Physical Development in Toddlers
and Infants
Chapter 4
Physical Development in Toddlers and Infants
• The beginnings—a rough start
– Prematurity: <37 weeks gestation
– Low birth weight: <5.5 pounds
– Very low birth weight: < 3.5 pounds
– Small for gestational age: <10th percentile of birth
weight for gestational age
Physical Development in Toddlers and Infants
• Infant Mortality:
– USA is 28th in the world in infant mortality in 1998
– USA overall infant mortality rate is 6.9/1000 births
• 14.1/1000 for African American babies
Infant Mortality
– Factors related to infant mortality
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Low birth weight
Prematurity
Congenital abnormalities
SIDS
Pregnancy complications
Respiratory distress
Infant Mortality
• Reducing Infant Mortality
– Modifying lifestyles
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Smoking
Substance abuse
Nutrition
Prenatal care
Contraception—young maternal age linked with
predictors of infant mortality
Infant Mortality
• Sudden Infant Death Syndrome
– Risk Factors
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Infant sleep position
Soft sleep surfaces
Loose bedding
Overheating
Smoking
Bed sharing/positional suffocation
Low birth weight or preterm infants
Growth of Body
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Cephalocaudal—head to toe; top to bottom
Proximodistal—center to extremeties
Newborn weight around 7+ 1
Newborns lose some weight
Rate of growth is most rapid in the initial few
months of life
Feeding and Nutrition
• CDC, WHO, Academy of Pediatrics: Human
milk is preferred over all other for infants with
no contraindications for breast mild (e.g. PKU)
• Breast feeding in regions with water quality
problems or sanitation problems can reduce
the incidence of infant mortality through
dehydration and diarrhea
• Potential for reinforcing bond between
caregiver and infant
Feeding and Nutrition
• Risks for Breastfeeding
– Maternal nutrition
– HIV/AIDS can be passed to nursing infants
– Cultural taboos—e.g. recent court case in Florida
Structure of the Brain and Nervous System
• Frontal Lobe- associated with reasoning,
planning, parts of speech, movement,
emotions, and problem solving
• Parietal Lobe- associated with movement,
orientation, recognition, perception of stimuli
• Occipital Lobe- associated with visual
processing
• Temporal Lobe- associated with perception
and recognition of auditory stimuli, memory,
and speech
Brain Development
• At approximately 20 weeks gestation:
– Brain has near the same number of neurons as full
term infant
– Development of neurons slows and development
of synapses or connections among neurons
(synaptogenesis)
– At approximately 30-31 weeks cerebral cortex
begins forming convolutions or folds
– At birth the neonate’s brain has the appearance of
the adult brain
Brain Development
• Establishment of myelin sheath (myelination)
continues far into childhood and adolescence
• Myelin sheath insulates the axon and
increases speed and efficiency of synaptic
impulse
• Development of motor function occurs as
myelin sheath develops in the motor areas of
the brain
Brain Development
• Pruning occurs as unused neurons die
• Pruning begins during fetal development and
continues across the lifespan
• Leads to diversion of nutrients to regions
more used
Method of Habituation to Study Sensation and
Perception
• Infants’ heart rates and rates and intensity of
sucking change with novel stimulation
• Steps in habituation studies
– Baseline data are collected with neutral stimulus
– Introduction of novel stimulus
– Change in response from baseline is recorded
– Over repeated presentation of stimulus systems
return to baseline
– Neutral stimulus is reintroduced
– Original novel stimulus is reintroduced
Sensory Systems
• Vision:
– At birth vision is blurry
• Focal length 8-15 inches
• Tends to focus at the center of the visual field
– Across development infants prefer
• Patterned objects to solid color objects
• Bright colors rather than pastels (3-6 months)
• Faces rather than other objects
– Facial preference: initially at hairline, then eyes,
then expression thus focal attention shifts
Sensory Systems
• Vision: Depth Perception—Visual Cliff
– Infants as young as 1-2 months react to
perceptual differences
– Mechanisms:
• Binocular vision and parallax
• Relative size of objects at different distances
• Relative motion
– Interactions between neurological maturation and
experience
Sensory Systems
• Auditory Sense
– Fetus reacts to loud noises as early as a few weeks
before birth
– Neonates sensitive to different sounds
– React to human voice differentially
– Early on (late neonatal period) infants can
distinguish caregivers’ voices from others
Sensory Systems
• Auditory Sense
– Adults and older children use code-switching
when interacting with infants
• Higher frequency
• Sing-song rhythm
• Rhyming
Sensory Systems
• Smell
– Breast fed infants recognize smell of mothers over
other females (pads in armpits or breast pads)
– Preference for breast milk regardless of whether
the infant is breast fed
• Taste
– Discriminate between sweet and sour tastes
Infant Cross-Modal Perception
• Synchrony—the co-occurance of two or more
stimuli
• Cross-Modal—two sensations in different
modalities (visual & auditory)
• Newborns can detect cross-modal synchrony
– Bouncing ball with sound
– Facial movement with speech
• Implications for language learning
Reflexes—Hardwired Systems
• Indicators of neurological and motor
development
• Primitive Reflexes
– Rooting and Sucking Reflexes
– Grasping
– Looming (depth perception)
– Babinski
• Checked to determine neurological maturation
Reflexes—Hardwired Systems
• Postural Reflexes
– Parachute reflex
– Locomotor reflexes
• Stepping
• Crawling
• swimming
Motor Development
• Gross Motor—large muscle groups
– Neck
– Torso
– Arms
– Legs
• Fine Motor—smaller muscle groups
– Finger & Thumb
– Refined grasping reflex (pincher motions)
Motor Development
• Bases for Motor Development
– Neurological Development
– Caregiver interactions and encouragement
– Opportunities for exercise & practice
– Maturation of Cognitive System
• Cultural Differences
– Wide variability in practices associated with
differences in ages of onset but generally, across
cultures, children tend to thrive with competent
caregiving
Toilet Training
• Key Elements
– Voluntary muscle control
– Awareness of the need
– Access to toilet
– Caregiver coach & praise
– Motive to control bladder and intestine
Toilet Training
• Readiness Signals
– Indications that infant/toddler needs changing
– Interest in toilet
– Asks for more mature underwear
• Child-set pace for toilet training seems to be
most adaptive strategy