Growth and development: Newborn and infant Flashcards
(33 cards)
Newborn: Weight
Average weight at birth: 3400g=7.5lbs
May lose up to 10% of birth weight without concern.
Should gain 0.5-1oz per day and should be back to birth weight by two weeks of age.
Weight should double by 4-6mo.
Weight should triple by 12mo.
Newborn: Length
Average length at birth: 50cm (20in)
Should increase by 50% at 12 mo.
Newborn: Head circumference
Average: 35cm (13.5in) at birth
Should increase by about 10cm at 12mo.
Systems immature at birth, that mature over the first year of life
Neurologic
Respiratory
Cardiovascular
Gastrointestinal
Hematopoietic
Renal
Immunologic
Integumentary
Newborn: Neurologic system
The CNS is not fully myelinated in infants.
Protective reflexes maintain equilibrium and persist for life.
Primitive reflexes are present at birth and disappear over time.
Involuntary movement progresses to voluntary control, and immature vocalizations and crying progress to the ability to speak as a result of maturational changes of the neurologic system.
Root reflex:
When infant’s cheek is stroked, the infant turns to that side, searching with mouth.
Disappears: 3mo.
Step reflex:
With one foot on a flat surface, the infant puts the other foot down as if to “step.”
Disappears: 4-8weeks
Suck reflex:
Reflexive sucking when nipple or finger is placed in infant’s mouth.
Disappears: 2-5mo.
Moro reflex:
With sudden extension of the head, the arms abduct and move upward, and the hands form a “C.”
Disappears: 4mo.
Asymmetric tonic neck reflex (Fencing position):
While lying supine, extremities are extended on the side of the body to which the head is turned, and opposite extremities are flexed (also called the “fencing” position).
Disappears: 4mo.
Plantar reflex:
Infant reflexively grasps with bottom of foot when pressure is applied to the plantar surface.
Disappears: 9mo.
Palmar grasp reflex:
Infant reflexively grasps when palm is touched.
Disappears: 4-6mo.
Babinski reflex:
Stroking along the lateral aspect of the sole and across the plantar surface results in fanning and hyperextension of the toes.
Disappears: 12mo.
Newborn-Respiratory:
the nasal passages are narrower.
the trachea and chest wall are more compliant.
the bronchi and bronchioles are shorter and narrower.
the larynx is more funnel shaped.
the tongue is larger.
there are significantly fewer alveoli.
These anatomic differences place the infant at higher risk for respiratory compromise.
The respiratory system does not reach adult levels of maturity until about 7 years of age.
The lack of immunoglobulin A (IgA) in the mucosal lining of the upper respiratory tract also contributes to the frequent infections that occur in infancy.
Newborn-Cardiovascular
The heart doubles in size over the first year of life.
As the cardiovascular system matures, the average pulse rate decreases from 120 to 140 in the newborn to about 100 in the 1-year-old.
Blood pressure steadily increases over the first 12 months of life, from an average of 60/40 in the newborn to 100/50 in the 12-month-old.
The peripheral capillaries are closer to the surface of the skin, thus making the newborn and young infant more susceptible to heat loss.
Over the first year of life, thermoregulation (the body’s ability to stabilize body temperature) becomes more effective: The peripheral capillaries constrict in response to a cold environment and dilate in response to heat.
Newborn: Gastrointestinal
The tongue is large relative to oral cavity size. The tongue extrusion reflex is necessary for sucking to be an automatic reaction—that is, when a nipple or other item is placed in the mouth, the tongue extrudes, and sucking begins.
The stomach capacity is relatively small at birth, holding about one half to 1 oz. However, by 1 year of age, the stomach can accommodate three full meals and several snacks per day.
On average, the first primary teeth begin to erupt between the ages of 6 and 8 months.
The consistency and frequency of stools change over the first year of life. The newborn’s first stools (meconium) are the result of digestion of amniotic fluid swallowed in utero. They are dark green to black and sticky. In the first few days of life, the stools become yellowish or tan. Generally, the formula-fed infant has stools the consistency of peanut butter. Breastfed infants’ stools are usually looser in texture and appear seedy.
Newborn: Genitourinary
In the infant, total-body water is a greater percentage of weight than it is in the adult. Thus, the infant is more susceptible to dehydration.
Infants urinate frequently, (Decreased bladder storage) and the urine has a relatively low specific gravity.
The renal structures are immature and the glomerular filtration rate, tubular secretion, and reabsorption as well as renal perfusion are all reduced compared to the adult.
The glomeruli reach full maturity by 2 years of age.
Newborn: Integumentary
Fine downy hair (lanugo) covers the body of many newborns..
At birth, the infant may be covered with vernix (earlier gestational age) or vernix may be found in the folds of the skin, axilla, and groin areas (later gestational age). Production of vernix ceases at birth.
The newborn and young infant’s skin is relatively thinner than that of the adult, with the peripheral capillaries being closer to the surface. This may cause increased absorption of topical medications.
Newborn: Hematopoietic system
During the last 3 months of gestation, maternal iron stores are transferred to the fetus. Healthy newborns typically have sufficient iron stores at birth. As the high hemoglobin concentration of the newborn decreases over the first 2 to 3 months, iron is reclaimed and stored. These stores may be sufficient for the first 6 to 9 months of life but will become depleted if iron supplementation does not occur.
Newborn: Immunologic system
Newborns receive large amounts of IgG through the placenta from their mothers.
This confers immunity during the first 3 to 6 months of life for antigens to which the mother was previously exposed.
IgM is produced in significant amounts after birth, reaching adult levels by 9 months of age.
Infants then synthesize their own IgG, reaching approximately 60% of adult levels at age 12 months.
Newborn Developmental Theories: Erikson
Trust vs. Mistrust (birth-1y)
Caregivers respond to the infant’s basic needs by feeding, changing diapers, cleaning, touching, holding, and talking to the infant. This creates a sense of trust in the infant.
As the nervous system matures, infants realize they are separate beings from their caregivers. Over time, the infant learns to tolerate small amounts of frustration and trusts that although gratification may be delayed, it will eventually be provided.
Newborn Developmental Theories: Piaget
Sensorimotor (birth to 2 years)
Infant uses senses and motor skills to learn about the world.
Substage 1: use of reflexes (birth to 1 month)
Reflexive sucking brings the pleasure of ingesting nutrition. Infant begins to gain control over reflexes and recognizes familiar objects, odors, and sounds.
Substage 2: primary circular reactions (1–4 months)
Thumb sucking may occur by chance; then the infant repeats it on purpose to bring pleasure. Imitation begins. Object permanence begins. Infant shows affect.
Substage 3: secondary circular reactions (4–8 months)
Infant repeats actions to achieve wanted results (e.g., shakes rattle to hear the noise it makes). The infant’s actions are purposeful, but the infant does not always have an end goal in mind.
Substage 4: coordination of secondary schemes (8–12 months)
Infants coordinate previously learned schemes with previously learned behaviors. They may grasp and shake a rattle intentionally or crawl across the room to reach a desired toy. Infant can anticipate events. Object permanence is fully present at about 8 months of age. The infant begins to associate symbols with events (e.g., waving goodbye means someone is leaving).
Newborn Developmental Theories: Freud
Oral stage (birth to 1 year)
Pleasure is focused on oral activities: feeding and sucking.
Newborn: Gross motor skills
1 month
Lifts and turns head to side in prone position.
Head lag when pulled to sit.
Rounded back in sitting.
2 months
Raises head and chest, holds position.
Head control is improving.
3 months
Raises head to 45 degrees in prone.
Slight head lag in pull-to-sit.
4 months
Lifts head and looks around.
Rolls from prone to supine.
Head leads body when pulled to sit.
5 months
Rolls from supine to prone and back again.
Sits with back upright when supported.
6 months
Tripod sits.
7 months
Sits alone with some use of hands for support.
8 months
Sits unsupported.
9 months
Crawls, abdomen off floor
10 months
Pulls to stand.
Cruises
12 months
Sits from standing position.
Walks independently.
