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
