Infant Terminology and Reflexes

Introduction

Every year there are an estimated 15 million babies born too early. Babies born before 37 weeks are considered preterm. Depending on the gestational age, preterm can be further divided into three sub-categories:

1. 32-37 weeks: moderate to late preterm
2. 28-32 weeks: very preterm
3. less than 28 weeks: extremely preterm

Complications from preterm birth include death, disability, learning disabilities and visual and hearing problems. Half of the babies born at or below 32 weeks die while almost all babies survive in high-income countries. Preterm babies that survive in middle-income countries have an increased burden of disability.

Often times preterm births occur spontaneously. Some of the known causes for preterm birth include:

• infections
• multiple pregnancies
• diabetes
• high blood pressure
• genetics

** Often times there is no reason for preterm birth.

affects reaching milestones when they were born

Birth weight

irth weight is 2,500 to 4,000 grams or five pounds, eight ounces to eight pounds, 13 ounces. Low birth weight is anywhere from 1501 to 2,500 grams. Very low birth weight is 1000 grams to 1500 grams and extremely low birth weight is an infant that weighs less than 1000 grams at time of birth. Now there are a number of

factors affecting birth weight: Such as ethnicity, the maternal age, maternal health, amount of maternal weight gain in pregnancy, birth order, gestational age, and genetics.

Apgar score

The apgar score is a quick test performed after birth to report the status of the newborn infant. The test consists of five components:

1. heart rate
2. respiratory effort
3. muscle tone
4. reflex irritability
5. color

Each factor is given a value from 0-2 with total scores being between 0-10. The apgar score is convenient, accepted and quick and reported at 1 and 5 minutes after birth.

Various ages

1. gestationsal
2. chronological
3. adjusted or corrected age- when they were born vs. when they were supposed to be- use this for milestone for the first two years of life

Primitive Reflexes

Primitive reflexes are involuntary survival-oriented motor responses. These reflexes develop in utero and strengthen postnatally. As the nervous system develops, these reflexes become integrated and diminish during the first three years of life. As neonates are not capable of cortically directed movements, primitive reflexes functionally provide the infants to interact within their environment. The absence or persistence of a reflex could indicate a neurological issue.Delays in primitive reflex integration correlates to reduced sensory processing and delayed milestones. Motor skills, coordination and balance may be affected with persistent reflex activity preventing the child from moving fluidly. Learning difficulties and behavioural problems are also linked to persistent reflex activity.

See below for a list of primitive reflexes:

Reflex	Description	Initiated	Integrated
Palmer Grasp	stroke palm of hand, grip finger	birth-2 months	4-11 months
Plantar Grasp	stroke sole of foot, toes curl	birth	9-12 months
Rooting	stimulus provided at cheek or lip and infants turns toward it	prenatal	3 months
Sucking	root of mouth touched, baby will suck	prenatal
Galant	strokes along paravetebral line activates trunk flexion toward stimulus	prenatal	3 months
Moro	when startled, arms, legs and neck into extension followed by arms together rapidly	birth	2 months
Babinski	stroke on foot from heel to toes, big toe moves upward-remaining toes fan out	3-4 months	12-24 months
Parachute	arms move forward if they perceive falling	5-9 months	persists
Stepping	holding baby under arm and feet touch surface, will simulate walking	birth	2 months
Flexor Withdrawl	noxious stimuli to the foot; foot withdraws using hip and knee flexion	prenatal	1-2 months
Crossed Extension	noxious stimuli applied to an extended leg; flexion on stimulus leg and weight shift and extension on contralateral side	prenatal	1-2 months
Proprioceptive Placing	brush the dorsum of the feet against the edge of a surface; will flex up hip and knee and lift foot up to surface then extend leg to accept weight through their leg	prenatal	2 months
Positive support	feet on contact surface in a weight-bearing suspension; infant accept weight through bilateral legs; extension of trunk, hip, knees	prenatal	1-2 months
Landau	prone in air supported; head, hips and back should extend	3-4 months	12-24 months

Tonic reflexes

Tonic reflexes elicit a holding response or cessation of movement. Once placed in a particular position the infant's muscles will stay contracted and hold that position.

Tonic Reflexes	Description	Initiated	Integrated	Purpose
Asymmetrical tonic neck reflex (ATNR)	with lateral rotation of the head, extension of the upper and lower extremity on face side, flexion on skull side	birth-2 months	4-6 months	motion in utero; promote early visual regard for hand; hand-eye coordination; break up symmetrical patterns
Tonic labyrinth	in prone, all limbs and head flex- in extension, all limbs and head extend	birth	6 months
Symmetric tonic labyrinth (STNR)	flexion of the neck causes flexion of the upper extremities and extension of lower extremities; neck extension elicits the opposite	4-6 months	8-12 months	assist with disappearance of flexion posture in prone to allow for quadruped; help with creeping

Righting Reactions

Righting reactions are automatic responses to maintain a normal upright posture.

Righting Reaction	Description
Optic Righting	using vision to maintain head in a vertical position
Labyrinth	using inner ear to maintain head in a vertical position when vision is obstructed
Neck Righting	when body is titled one way, neck maintains head in vertical position
Vertical Righting	when body is titled one way, neck and trunk on opposite side of shift will shorten to maintain vertical position
Rotational Righting	body on body: flexing either an upper or lower extremity and crossing it over midline to initiate rolling head on body: as head rotates the body will follow for rolling

Resources

• Reflexes
• Primitive Reflexes