Fetal development Flashcards
When are the terms embryo and fetus appropriate
Embryo is appropriate until 8 weeks of gestation, and then at week 9, becomes a fetus
When is it considered structurally complete
Week 8
Fetal weeks 9-12
Genitals well differentiated Tooth buds appear Cerebellum develops Red blood cells produced by liver Growth of all existing structures
Fetal weeks 13-16
Skin is almost transparent Lanugo develops on the head Meconium is made in the intestines Muscles and bones develop, bones are still soft Sucking motions are made with the mouth
Fetal weeks 17-19
Can hear Mother can feel movement Spinal cord myelination begins Eyebrows and lashes form Nails form; at 20 weeks, sensory portion of auditory system (inner ear) has attained adult shape
Trimester weeks
First trimester: conception through week 13
Second trimester: week 14 through 26
Third trimester: week 27 to 40
Fetal week 21-23
Fetal heartbeat can be heard with a stethoscope
Bone marrow makes blood cells
Fat is stored
Weeks 23-24
Lower respiratory system develops but still no surfactant
50% chance of survival
Between 23rd and 25th week, then survival increases
23 to 24 weeks gestational age at birth
Lung viability depends on surfactant- not yet present, provide in NICU
Survival Depends on weight, family values and beliefs
Slow active movement of hands to face
Very sporadic flailing movement patterns
24 weeks gestation
All eye parts present
Foot and handprints form
25-28 weeks
Rapid brain development
Eyelids open and close
Gas exchange is weak but present
27 to 28 weeks outside womb motor patterns
Resting postures:
– Generalized hypotonia • Resistance to passive movement:
– Full PROM
– Grasp response elicits only
the arm back into flexion – No attempt to align head and
body with pull to sit (PTS) – No placing response
• Active motor patterns:
– Spasmodic and random flailing
No t for reproduction or redistribution
flexion of the fingers without activation of the wrist and arm
– No resistance in heel to ear
– Popliteal angle: 180 degrees
– Scarf sign, no attempt to recoil
28 weeks gestation outside womb oral motor
Weak but present non-nutritive suck (NNS) • Rooting reflex long latency period, slow response to
oral stimulation:
– Mouth opening only may be seen
Fetal development 29-32 weeks
Body fat deposited rapidly
Rhythmic breathing movements
Begins to store calcium and iron
29 weeks gestational age outside womb motor
Resting postures:
– More variability in postures; remains hypotonic • Resistance to passive movement:
– Full PROM; movement of one extremity may elicit movement in the
opposite extremity – Moro incomplete but symmetrical – No resistance in the scarf sign; elbow crosses midline; may move UE back
to the same side of the body after placing – In prone, the infant attempts physiological flexion by moving LEs into a
flexed posture – Complete head lag; attempt to right head once anteriorly placed in
supported sitting – Mild active knee flexion with eliciting of the placing response – Stepping response is elicited with mild neonatal support
29 weeks active motor patterns
Slow, jerky, random flailing – Reflexive movements in response to handling – LE predominate motor patterns; LE presenting in the
beginning of the physiological flexion patterns
28 to 30 weeks vision
Increases in waking phases • Eyes remain closed for the majority of the time • Doll’s eye reflex may be observed 1 • Saccadic eye movements:
in apnea or brady
– Rapid – Intermittent – Jerky
• Visual stimulation may increase stress levels and result
30 weeks motor pattern after birth
Resting postures:
– Flexion of the hips and knees • Resistance to passive movement:
– Grasp response with initial flexion of the wrist and knee; the traction
response begins to elicit the lifting of the infant off the support surface – Beginning resistance in heel to ear – Scarf sign attempts to recoil the arm back into flexion – Once in supported sitting, the infant attempts anterior and posterior
righting of the head when displaced posteriorly or anteriorly – Minimal to no attempt WB through LEs in neonatal stance, but the feet do
elicit a response against the support surface
• Active motor patterns:
– Whole extremity movement with attempt to bring to midline
30 weeks hearing
Th e middle ear at 30 weeks:
No t for reproduction or redistribution
– Transmission portion – Development complete – Once respiration occurs at birth, then air enters the
middle ear cavity
31 weeks motor after delivery
Resting postures:
righting reaction anterior and posteriorly – No active WB through LE with neonatal
• Active movements:
– Active flexion and extension patterns against gravity
remain random and uncoordinated
No t for reproduction or redistribution
– Physiological flexion seen in the LEs • Resistance to passive movement:
– Resistance to PROM in the LEs; decrease in heel to ear
– Attempts to maintain head in midline with body in PTS;
32 weeks motor
Resting postures: – Increase in physiological flexion; knees and hips have no resistance in heel to ear • Active movements: – Increase in purposeful movements – Hand to mouth for self calming
32 weeks motor resistance to passive movement
Re sistance to passive movement:
No t for reproduction or redistribution
– Increase in activation of the wrist, forearm, and arm (UE
traction response) – Popliteal angle: 150 degrees – Dorsiflexion angle: 40 to 50 degrees – PTS increase attempt to align head in midline with body – Begin eliciting WB in neonatal stance; extension of the
knee (leg onto the thigh) and attempt to extend trunk on
pelvis – Moro reflex with complete extension and adduction;
extension of the fingers
32 weeks oral motor
Stronger sequencing of NNS • Rooting complete with mouth opening and turning of the head toward oral stimuli
30 to 32 weeks vision
Increase in ability to maintain awake alert state • Pupillary light reflex • Monocular vision • Bright light causes immediate closing of eyes • Focus on visual stimuli for short periods • All other body movements stop when the visual system
is engaged • No preference of visual patterns • Horizontal visual tracking from midline for short
distances
33 weeks motor
Resting postures:
– Continued increase in flexion of the LEs with knees and hips • Resistance to passive movement:
– Knee flexion stronger; decrease in heel to ear
– Recoil and traction response of (B) U/LEs
– PTS stronger attempt to right the head anteriorly with the body; once
displaced anteriorly or posteriorly, attempts to right the head to midline – Supportive stance, WB on LEs with trunk and knee extension; attempts to
right the head with the trunk as well – Palmar grasp +
• Active movements:
– Spontaneously flexes and extends U/LEs; smoother motor patterns but
they remain random and flailing – Ability to bring hands to the mouth for self calming
When does surfactant develop
34 weeks
34 weeks motor patterns
Resting postures:
– Physiological flexion, excessive ER and ABD “frogged
position”
• Active movements:
– Active vigorous flexion and extension of LEs; increase in
purposeful and reciprocal movements against a boundary – Activation of the lumbosacral joint
34 weeks resistance to passive movement
Grasp and UE reaching into the scapulo-humeral joint; the
trunk can be raised off the support surface – Physiological flexion of the LEs with full flexion posture – Popliteal angle: 110 degrees – Attempting to right the head in supported sitting in all directions – Placing response elicited – Hips and knees extended in a supportive stance; beginning of
trunk activation – Ventral suspension elicits flexion of the elbows and knees with
very small effort to lift the head against gravity – Moro extends and abducts, followed by partial flexion and
adduction
34 weeks oral motor
Grasp and UE reaching into the scapulo-humeral joint; the
trunk can be raised off the support surface – Physiological flexion of the LEs with full flexion posture – Popliteal angle: 110 degrees – Attempting to right the head in supported sitting in all directions – Placing response elicited – Hips and knees extended in a supportive stance; beginning of
trunk activation – Ventral suspension elicits flexion of the elbows and knees with
very small effort to lift the head against gravity – Moro extends and abducts, followed by partial flexion and
adduction
35 weeks vision
Tracking horizontal past midline • May track vertical • Visual preference beginning:
– Faces – Contrasting colors
35 weeks fetal development
Brain myelination begins and continues until 1 year gestational age
36 weeks fetal development
Lanugo begins to disappear
35 weeks motor patterns
Resting postures:
– Increase in physiological flexion; more flexion of both U/LEs against gravity
• Resistance to passive movement:
– Moro partially complete; extension and abduction with flexion and
• Active movements:
– Alert periods; active transition to alerting state prior to feeding; attempting
to self calm with hands to the mouth and/or facial area
No t for reproduction or redistribution
adduction – Increase resistance to PROM LE over UE – Prone with head in midline; active rotation of head to both directions – PTS righting of the head and attempts to maintain the head in alignment
with the body – Increase active WB through LEs in supported stance; knees and hips
extended; trunk and head attempting to maintain alignment
37 to 40 week fetal
Small breast buds appear on both sexes due to mom’s hormones
At 40 weeks: Full-term and adequate surfactant to sustain life; all primitive reflex patterns are present and symmetrically elicited in the full-term infant
36 to 37 weeks motor
Resting postures:
– Increased variety of resting postures
– Physiological flexion in trunk and extremities • Resistance to passive movement:
– All newborn primitive reflexes are elicited
– Traction/grasp response is elicited; the trunk and head maintain
No t for reproduction or redistribution
alignment with the body, but are unable to sustain the flexion – Moro is complete – Resistance to knee extension and hip extension and abduction – Quicker recoil / flexor withdrawal – Attempt to maintain head in alignment with the body in PTS – In the prone position, the infant’s hips are high, with the knees
under the pelvis – Stepping and placing responses
36 to 37 weeks active movement
– Variability in resting postures – Active movements are more resistant by physiological
flexion – Active hands to mouth
