Infancy
Development During Infancy
Physical Development
Weight and Length
The primary focus of a newborn during its first month of life is the stabilization of organ systems and adjustment to life outside the womb.
The average weight for a newborn is between 5 lb 8 oz to 8 lb 13 oz.
Weights outside of this range may be associated with premature births or gestational diabetes.
The average length for a newborn is 18 to 22 inches.
Notably, the arms are typically slightly longer than the legs.
The Head and Skull (Neonatal)
The head of the newborn measures about one-fourth of the total body length and has a circumference of 13 to 14 inches.
It is common for the shape of the skull to appear abnormal for a few days after birth due to the pressure applied during a vaginal birth, a phenomenon known as cephalic molding.
The skull consists of six bones separated by sutures made of cartilage.
The soft spots on the infant’s head, known as fontanels, allow the brain to grow rapidly during early life.
Respiration
The most critical change following birth is the establishment of respiration.
Pressure on the baby’s chest during a vaginal birth helps remove amniotic fluid from the lungs.
On average, a newborn's respiration is:
Irregular
Shallow
Between 30 to 50 breaths per minute
Brief episodes of periodic breathing are considered normal.
Cardiovascular System
The newborn's body transitions from placental blood flow to independent circulation.
The average heart rate for a newborn ranges from 120 to 140 beats per minute (bpm); variations may occur during rest or crying.
It's normal for a newborn’s hands and feet to appear blue at birth, which usually resolves within a few hours.
Thermoregulation
A newborn's body temperature is generally close to that of an adult.
Newborns can produce adequate heat but struggle to retain it.
Guidelines for maintaining warmth include:
Avoid placing the baby on cool and uncovered surfaces.
Ensure the room temperature is not too cold.
Keep the newborn warm and dry.
A cap should be placed on the newborn’s head.
Elimination
Kidneys
After birth, newborns' kidneys produce between 15 to 60 mL of urine per kilogram of body weight per day.
During the first 24 hours, a newborn typically voids between 5 to 25 times.
Newborn kidneys have a limited ability to concentrate urine.
Bowel
After birth, the newborn’s intestinal tract contains meconium, which should pass within the first twelve hours.
Following this, stools should transition to a yellow color.
Gastrointestinal System
A full-term infant can digest proteins and simple carbohydrates.
Stomach capacity varies from 30 mL to 90 mL.
Normal colonic bacteria are typically established within the week following birth.
Epidermis and Dermis
Newborn skin is thin and fragile, characterized by several terms:
Vernix caseosa: A protective covering on the skin, often described as akin to cheese.
Milia: Small white spots commonly found on the newborn’s skin.
Congenital dermal melanocytosis: A dark pigmented area usually observed on the buttocks or lower back.
Many unique and harmless features found on infants will typically disappear over time.
Neuromuscular Development
Newborns exhibit numerous reflexes that can be tested to assess their health status:
Rooting reflex
Sucking reflex
Swallowing reflex
Grasp reflex
Tonic neck or fencing reflex
Moro or startle reflex
Stepping reflex
Crawling reflex
Babinski reflex
Cognitive Development
Cognitive Development encompasses:
Reflexive – purposeful motor actions.
Learning through doing, highlighting the cause and effect relationship.
Increased vocalizations including:
Cooing (Imitating Sounds)
Approximately 4 to 5 words by 12 months.
Sensory Development
Improved vision (refinement in both acuity and color perception).
Enhanced hearing capability; infants show enjoyment in cooing and laughing.
Milestones
Milestones include:
3 Months – Smiling.
5-6 Months – Able to roll both ways (from back to tummy and tummy to back).
7 Months – Sitting unassisted.
9 Months – Crawling.
10 Months – Achieving pincer grasp.
11 Months – Cruising (movement while holding onto objects).
12 Months – First steps, development of object permanence, and usage of simple gestures/words.
Object Permanence Example: If a toy is hidden under a blanket, a younger infant may forget about it; but when they develop object permanence, they will lift the blanket to look for the toy.
Psychosocial Development
The central task for infants during psychosocial development is the establishment of trust.
The caregiver-infant relationship plays a crucial role in building a sense of trust through:
How caregivers respond to infant discomfort.
Providing comfort through cuddling.
Offering appropriate stimulation.
Theories and Stages
According to Freud, infancy falls within the oral stage, where infants derive pleasure from sucking.
Infants develop abilities to self-soothe and occupy themselves through oral stimulation, such as sucking on pacifiers, toys, or their hands.
By around 2 or 3 months, infants typically begin to smile in response to others.
At 9 months, infants increase interaction and socialization with others, engaging in simple games such as peek-a-boo and patty-cake.
Common Health Problems
Crying and Colic
Crying serves as a normal communication method for infants indicating needs such as hunger, discomfort, or temperature changes.
Healthy infants may experience daily fussiness lasting 1 to 2 hours.
Colic is characterized by extended crying due to frequent abdominal pain and marked inconsolability, with an unknown cause that generally resolves by around 3 months of age.
Failure to Thrive
Infants depend entirely on caregivers for nutrition, comfort, warmth, and love.
Lack of a nurturing, responsive relationship can lead to failure to thrive, signified by poor weight gain, delayed development, malnutrition, and challenges in forming future bonds.
This is often evident in environments where families lack support or understanding of infant needs.
Erikson emphasized that this condition illustrates the crucial importance of the trust-versus-mistrust stage in early development.
Tooth Decay
Tooth decay may develop by the end of the first year when infants are put to bed with bottles containing anything other than water.
Sugary fluids such as breast milk, formula, or juice can accumulate in the mouth, potentially resulting in carious lesions (cavities).
Sudden Infant Death Syndrome (SIDS)
SIDS is defined as the abrupt death of a previously healthy infant with no explainable cause.
It is believed to relate to abnormalities in the infant’s brain that regulate breathing and arousal during sleep.
The peak risk for SIDS is between 3 and 4 months of age, but it can occur up to 12 months.
Risk Factors for SIDS
Several factors can elevate the risk of SIDS, including:
Prematurity
Low birth weight
Being male
Identifying as African American/Black
Exposure to smoking in the household
Swaddling practices
Placing infants to sleep on their stomachs
Recommended practices to reduce SIDS risk include placing babies on their backs to sleep, breast-feeding, and providing a pacifier during naps and bedtime as additional protective measures.
Jaundice
Two to three days post-birth, the red blood cell count declines, causing an increase in bilirubin production.
Elevated levels of bilirubin result in a yellowing of the skin.
If bilirubin accumulates excessively and reaches the brain, it may lead to neurological damage.
Phototherapy is a treatment often employed to help break down bilirubin in the infant’s skin.
Other Important Points
Regularly assess for signs and risks of abuse in infants:
Shaken Baby Syndrome
Infants requiring extensive care
Infants from families undergoing employment stress
Infants from families that frequently move
Car Seat Safety:
Children should remain rear-facing until meeting growth requirements.
Notably, in Sweden, it is culturally accepted for children up to age 4 to remain in rear-facing car seats, contributing to some of the lowest child traffic fatality rates globally (Macy, 2015).
The APGAR Score serves as a preliminary examination addressing appearance, pulse, grimace, activity, and respiration.
Research consistently underscores that early identification and intervention for at-risk neonates not only enhance short-term outcomes but also diminish long-term complications (Zhang, 1992).