Primitive reflexes and when they disappear
- Concept
Newborns have automatic reflexes from the brainstem and spinal cord; they fade as the cortex matures, and if they persist they point to brain injury.
What it is
Primitive reflexes are automatic movements present at birth, organized in the brainstem and spinal cord. As the cerebral cortex and its descending pathways mature in the first months, they are inhibited and give way to voluntary movement and postural reactions. Their absence, asymmetry or persistence beyond the usual age suggests a problem of the nervous system or of a limb; the ages below are usual ranges and vary between sources.
Key facts
- The extensor plantar response (Babinski sign) is normal in infants and usually becomes flexor in the second year, as the corticospinal tract myelinates.
- Reflexes that stay normal for life include blinking, coughing, gagging, sneezing and yawning.
- The asymmetric tonic neck reflex has to fade before the baby can roll and bring both hands to the midline.
- Postural (protective) reactions such as head righting and the parachute replace the primitive reflexes.
Main primitive reflexes, how they are elicited and when they usually fade
| Reflex | How it is elicited and the response | Usually fades by |
|---|---|---|
| Moro | Head allowed to drop back briefly: arms open, then come together; often cries | 3 to 4 months (6 at the latest) |
| Rooting | Stroking the cheek: turns toward the touch and opens the mouth | About 4 months |
| Sucking | Touching the lips or palate: rhythmic sucking | About 4 months (becomes voluntary) |
| Palmar grasp | Finger in the palm: the hand closes | 4 to 6 months |
| Plantar grasp | Pressure under the toes: the toes curl | 9 to 12 months |
| Asymmetric tonic neck | Head turned to one side: arm on the face side extends, the other flexes | 4 to 6 months |
| Galant (trunk incurvation) | Stroking along the spine, baby prone: the trunk curves toward the side touched | About 4 to 6 months |
| Stepping (placing) | Held upright with soles on a surface: stepping movements | About 2 months |
Clinical notes
- Bilaterally absent Moro in a newborn suggests a severe central problem, such as hypoxic-ischemic encephalopathy, or deep sedation.
- Primitive reflexes that persist or reappear, with increased tone, are early signs of cerebral palsy.
- In adults, frontal release signs (grasp, snout, palmomental) reappear in frontal lobe damage and advanced dementia.
Test yourself
Think of the answer, then tap the question to see it.
By what age does the Moro reflex usually disappear?
By about 3 to 4 months, and at the latest around 6 months.
What does a Moro reflex absent on one side only suggest?
A problem of that arm: brachial plexus injury or a fracture of the clavicle or humerus.
Why do primitive reflexes disappear?
Because maturing cortex and descending pathways inhibit the brainstem and spinal reflex circuits.
Which protective reaction appears at about 8 to 9 months and lasts for life?
The parachute reaction: the arms extend forward when the baby is tipped forward.
Elsewhere in DurgiPedia
Connections
Educational content on behavior and the clinical relationship; not a diagnostic or treatment guide and no substitute for assessment by a health professional. If you or someone near you is at risk, seek help now from an emergency service or a mental-health helpline.
Sources: Infant reflexes (MedlinePlus, U.S. National Library of Medicine, 2025); Moro reflex (MedlinePlus, U.S. National Library of Medicine, 2025).
Spotted a mistake?We are always improving for the community. Tell us what is wrong and our team will review it.Report a mistake
Representative model, for educational purposes only.