Newborn Reflexes
Overview
Newborn (primitive) reflexes are involuntary motor responses mediated by the brainstem and spinal cord. Their symmetric presence confirms neurological integrity; absence or asymmetry suggests CNS damage, birth trauma, or peripheral nerve injury. Each reflex appears at birth (sucking by ~32 weeks gestation) and disappears on a predictable timeline as the cortex matures — persistence beyond the expected age or an asymmetric response is the abnormal finding.
Interpretation
High-yield primitive reflexes — how to elicit and when each normally disappears. A symmetric response is expected; an asymmetric or absent response in a term newborn is the concerning finding.
Technique
Eliciting the Moro reflex correctly — the single most clinically loaded newborn reflex because symmetry, not mere presence, is the assessment parameter.
Patient Teaching
Reassuring caregivers about normal reflex behavior and what is age-appropriate.
REPORT NOW — absent or asymmetric primitive reflexes signal neurologic injury or birth trauma and require provider notification.
Clinical Pearl
Moro should be a mirror — both arms out, both arms in. If one arm stays still, think clavicle fracture or Erb palsy and report immediately.