Infant Growth and Development Flashcards
intra-uterine growth
embryonic and fetal
growth (assessed by birthweight)
gestational age
Post-menstrual age
* ie. number of weeks + days since 1st day of last menstrual period
What is full-term?
38-42 weeks post-menstrual age
What is considered pre-term?
<37 weeks
What is considered low birthweight?
<2500 g at delivery
How is newborn growth assessed?
Measurements of length, weight, head circumference are done at delivery and assessed using growth charts
* Throughout pregnancy women is measured for size and then compared to infant measurements → provides information about patterns of intra- uterine growth
When do adaptations happen which effect a newborn?
Adaptations occur in-utero to adverse circumstances
* increase short-term survival
* permanent alterations in structure or function occur during “critical periods” of development
What are the patterns for intra-uterine growth?
- Small for gestational age (SGA): Weight for age <10th percentile
- Appropriate for gestational age (AGA): Weight for age 10-90th percentile
- Large for gestational age (LGA): Weight for age >90th percentile
What is the birthweight classification used for?
Method of describing the likelihood of adverse outcomes
* type of problem depends on birthweight classification and etiology (cause)
Factors affecting etiology of SGA
- infant factors
- placental factors
- maternal factors
Infant factors affecting etiology of SGA?
- congenital anomalies
- genetic conditions
- congenital infections
placental factors affecting etiology of SGA
- small placenta
- inadequate placental blood flow
maternal factors affecting etiology od SGA?
(“environmental”)
* smoking
* alcohol
* drugs
* undernutrition
Risks associated with SGA
- hypoglycemia → not getting enough glucose outside of the uterus
- inability to maintain temperature, if fat not laid down
- ↓ immune competence
- (neurologic & behavioral problems) → multi-factorial
what are long term risks of SGA related to?
Typically in utero adaptations
infant factors effecting etiology of LGA
genetics
Maternal factors affecting etiology of LGA
uncontrolled/poorly controlled diabetes
* Many LGA babies not at ↑ risk, but infant of a diabetic mother (IDM) is at ↑ risk
Risks associated with all LGA
birth injury both the mom and baby
Risks associated with IDM with LGA
- hypoglycemia
- hypocalcemia
- respiratory, cardiac problems, congenital malformation (3-4 x risk)
What is IDM
Infants of Diabetic Mothers
How do growth charts work?
Variability at given age defined by percentiles which is proportion of population found below a specific value
* Age along x-axis; anthropometric (weight, length, head circumference) measure on y-axis
* Also weight for length: length x-axis; weight measure on y-axis
What is the expected pattern along the growth chart for an infant?
Maintenance of growth along “own” percentile
* Birthweight reflects prenatal growth factors, postnatal growth dependent on different factors including genetic potential
* Crossing percentiles between 0 and 24 months not uncommon
When is it important to do a follow up in an infants growth pattern?
- flat growth line
- sharp increase or decrease
- below 3rd percentile
- above 97th percentile weight for length
What are important considerations considering growth patterns?
Consider birthweight, previous growth pattern, gestational age, genetics, type of feeding, presence of a condition/disease
What is the expected pattern for infant growth?
- Double birth weight by ~4 months
- Triple birthweight by ~1 year
Assessing growth in preterm infants
specific pre-term growth chart such as the Fenton Growth Chart and uses data starting at 22 weeks gestational age
* switch to full term charts when within gestational and measurement ranges using corrected age
How is corrected age determined for pre-term infants?
Corrected age in weeks
* current age (weeks since birth) minus (40 weeks – gestational age at birth in weeks)
* assumes full term at 40 weeks
What are the adaptations to post natal life?
- Physiological – gastrointestinal function to learn to digest
- Protective – mucosal barrier function noe exposed to environment
- Biochemical – metabolism
- Developmental (Mechanical/Motor) - feeding
Gastrointestinal development prior to pregnancy
The gastrointestinal tract is formed prior to third trimester
* Third trimester: ingestion of amniotic fluid prepares gastrointestinal tract for nutrients
* Gastrointestinal motility mostly developed; coordination of peristalsis matures early infancy
Digestion and absorption ability at birth
At birth able to digest components of breastmilk as efficiently as adults
* disaccharidases present in near-adult levels; lactate activity increased rapidly with feeding
* pancreatic amylase low so poor starch digestion
* fat digestion/absorption slightly lower than adult; short and medium chain better absorbed
* transporters present on brush border
What is the glomerular filitration rate?
Rate at which electrolytes, water and waste products are transferred from the circulation into the kidney
How does renal function adapt with post-natal?
- Birth: ~30% adult level
- 1 year: ~70% adult level
- 3 years: 100 % adult level
What is RSL?
renal solute load - Electrolytes and urea to be excreted
What is normal for RLS?
Low RLS
When does RLS increase?
Increased RSL with high protein
* increased water for excretion and/or reduced excretion of wastes
Adaptation of protective GI functions
Development of mucosal gut barrier gradual in infancy
What are the protective mechanisms of the infant gut?
- gastric barrier, proteolysis, peristalsis, factors in breastmilk
- mucosal coat and microvillus membrane
- antibodies (IgG, sIgA), other substances
What is the major metabolic change that occurs at birth?
The loss of a constant supply of glucose
* plasma glucose decreases at birth leading to a reduction in insulin and increase in glucoagn
What is the adaptation during in utero to prepare the baby for loss of glucose at birth?
glycogen and triglyceride synthesis and storage during the third trimester is used during the metabolic adaptations at birth
* allows for glycogen breakdown, lipolysis, gluconeogenesis
awareness newborn
- birth: initially vigorous and alert 30-60 min
- subsequent: 80% sleep, 20% active, inactive or crying
How does tone of a newborn develop?
flexion develops from lower to upper limbs 28-40 weeks supporting the feeding response
What is the firs thing done for a term newborn?
APGAR score: given 1 min after birth and then again at 5 min to quickly assess overall health and see if infant needs any medical attention with a score ranging from 0-10, 10 being rare
* 8-10 is good
* 5-7 may need some attention
* 0-4 need emergency medical attention
What does AGPAR stand for?
- Appearance: skin color
- Pulse: heart rate
- Grimace: response to stimulation
- Activity: flecion (muscle tone)
- Respiration: respiratory effort (2-strong, 1-weak cry, 0-no cry/not breathing)
What are primitive reflexes?
involuntary movements that reflect normal nervous system development
* some important for normal feeding behaviour at birth
* gradually dissapear with maturity and should be gone by 6-12 month
What are important primitive reflexes for feeding?
- rooting
- sucking
- moro
- head lag/step
- grasping
rooting reflex
head turning toward stroked face
* usually integrates about 3 months of age with more head control
sucking reflex
reflexive, not voluntary
* in utero as well
Moro reflex
“startle” reflex - arms more outward, than toward body, then might cry
* integrates about 3-5 months
head lag/step reflex
- head movement during pull to sit
- stepping movement when held upright
What movements/ reflexes are needed to breastfeed?
grasp nipple, suck, swallow, breathe
What movements are needed for baby foods/purees?
- tongue movement to move food back
- upright posture/ head control
movements need for finger feeds -self feeding
- grasp, hand to mouth (hand-eye coordination)
- tongue movement side to side
- upright posture/ head control
Movements needed for cup drinking
- hands & object to mouth
- tilt head & cup backward
- control free flowing liquid
Movements needed for table food
- collect particles of food in bolus for swallowing
- push food to side of gums/teeth for chewing
developmental milestone at birth
grasp nipple, suck, swallow
developmental milestones 4-6 months
grasps objects, improved head control, some vocalization (ah, goo)
* should be able to reach out and grasp objects
developmental milestones 6 months
transfers objects hand-to-hand, hand to mouth, sits with support, 1st teeth (front), expresses food preferences
developmental milestones 7-8 months
sits independently, more vocalization (mama, dada)
developmental milestones 9 months
pincer grasp, cruising on furniture
* like a cheerio
developmental milestones 12-15 months
walking, words, 1st molar
