Your newborn’s paediatrician checked a series of reflexes at birth. Your occupational therapist mentioned “primitive reflexes” in your child’s assessment. You’ve seen the term in autism and developmental delay discussions online. But what exactly are primitive reflexes, why do they matter, and what happens when they don’t disappear on schedule? This complete guide answers all of that.
What are primitive reflexes? Primitive reflexes are automatic, involuntary movement patterns present in newborn babies, controlled by the brainstem. They are essential for early survival and should gradually integrate (disappear) between 4 and 12 months of age. If they persist beyond this — called retained primitive reflexes — they can affect motor development, sensory processing, attention, and learning.
Complete Guide — Jump to Any Section
- What Are Primitive Reflexes? Definition and Science
- The Full List of Primitive Reflexes
- The 5 Most Important Primitive Reflexes
- What Are Reflexes in Child Development?
- When Should Primitive Reflexes Integrate?
- Why Do Doctors Check Infant Reflexes?
- Reflexes Tested in Newborns in India
- Brisk Reflexes and Slow Reflexes
- Primitive Reflexes and Autism
- Frequently Asked Questions
1. What Are Primitive Reflexes? Definition and Science
A reflex is an automatic, involuntary movement response to a stimulus. In newborns, the most important reflexes are called primitive reflexes because they originate in the brainstem. They follow a specific developmental trajectory: present at birth for survival, then integrating as the higher brain develops control. The word “integrate” means the reflex is absorbed into voluntary control — it stops triggering automatically.
2. The Full List of Primitive Reflexes
1. Moro Reflex (Startle Reflex)
Trigger: Sudden movement, loud sound, or sensation of falling. Response: Arms fling outward, fingers spread, then return. If retained: Anxiety, excessive startle, sensory hypersensitivity. See our Moro reflex guide.
Integrates: 4–6 months2. Rooting Reflex
Trigger: Touch on the baby’s cheek. Response: Head turns toward touch, mouth opens. If retained: Oral hypersensitivity, speech articulation difficulties. See rooting reflex guide.
Integrates: 3–4 months3. Palmar Grasp Reflex
Trigger: Touch or pressure on the palm. Response: Fingers curl and grip tightly. If retained: Fine motor difficulties, hypersensitive hands, handwriting grip problems.
Integrates: 5–6 months4. ATNR (Asymmetric Tonic Neck Reflex / Fencer Reflex)
Trigger: Turning the head to one side. Response: Same-side arm and leg extend; opposite arm and leg flex. If retained: Difficulty crossing the midline, letter reversals, reading and writing challenges.
Integrates: 6 months5. TLR (Tonic Labyrinthine Reflex)
Trigger: Head position relative to gravity. Response: Head position affects muscle tone throughout body. If retained: Poor posture, balance difficulties, motion sickness.
Integrates: 6–12 months6. STNR (Symmetric Tonic Neck Reflex)
Trigger: Bending or extending the neck. Response: Neck flexion causes arm flexion and leg extension. If retained: W-sitting, poor posture, skipped crawling.
Integrates: 9–11 months7. Babinski Reflex
Trigger: Stroking the outer edge of the sole upward. Response: Big toe extends upward and other toes fan out. Note: Persistence beyond age 2 in healthy children warrants neurological assessment.
Integrates: 12–24 months3. The 5 Most Important Primitive Reflexes
| # | Reflex | Trigger | Integrates By | If Retained: Affects |
|---|---|---|---|---|
| 1 | Moro | Sudden movement/sound | 4–6 months | Anxiety, fight-or-flight, hypersensitivity |
| 2 | Rooting | Cheek touch | 3–4 months | Oral sensitivity, speech articulation |
| 3 | Palmar Grasp | Palm pressure | 5–6 months | Fine motor, handwriting, tactile sensitivity |
| 4 | ATNR | Head turning | 6 months | Reading, writing, midline crossing |
| 5 | TLR | Head position/gravity | 6–12 months | Posture, balance, spatial orientation, motion sickness |
4. What Are Reflexes in Child Development?
Immediate Survival Function
Rooting helps newborns find food. Moro triggers help-seeking. Grasping helps babies hold on.
Builds Voluntary Movement
Each reflex exercises neural pathways that will later be used for voluntary movement. ATNR exercises eye-hand coordination circuits that enable reading and writing.
Neurological Report Card
The presence, timing, and integration of primitive reflexes gives doctors direct information about neurological health — assessed at every well-baby check-up.
5. When Should Primitive Reflexes Integrate?
| Reflex | Expected Integration | Concern if Persisting Beyond |
|---|---|---|
| Rooting | 3–4 months | 6–7 months |
| Moro | 4–6 months | 6 months |
| Palmar Grasp | 5–6 months | 6 months |
| ATNR | 6 months | 6–7 months |
| TLR | 6–12 months | 12 months |
| STNR | 9–11 months | 12 months |
| Babinski | 12–24 months | 24 months |
6. Why Do Doctors Check Infant Reflexes?
- Confirming brainstem integrity: Present and symmetric reflexes confirm normal neurological function — checked immediately after birth.
- Detecting neurological problems: Absent reflexes, asymmetric reflexes, or very weak reflexes can indicate neurological problems requiring immediate investigation.
- Tracking developmental progress: Persistent primitive reflexes at 9, 12 months or beyond are developmental flags.
7. Reflexes Tested in Newborns in India
At standard newborn check-ups in Indian hospitals, paediatricians test: Moro reflex, rooting reflex, sucking reflex, palmar grasp reflex, plantar grasp reflex, stepping reflex, tonic neck reflex, and Babinski reflex. What reflexes are tested in infants will be repeated at 1, 3, 6, and 9-month check-ups, tracking integration progress. If you have concerns, ask for a referral to an occupational therapist specifically for primitive reflex assessment.
8. Brisk Reflexes and Slow Reflexes
What are brisk reflexes? Tendon reflexes (knee-jerk, bicep, ankle) that are stronger or more exaggerated than typical. In the context of autism, brisk reflexes are sometimes reported as part of neurological examination findings — one piece of a larger clinical picture.
What are slow reflexes a sign of? Reduced neurological responsiveness, muscle weakness, or nerve issues. Always context-dependent — age, other neurological findings, and overall developmental status matter.
9. Primitive Reflexes and Autism
Many autistic children show atypical reflex patterns, including retained primitive reflexes beyond expected integration ages. Retained reflexes are not caused by autism, and don’t cause autism — both may reflect underlying neurological development differences. Retained reflexes in autistic children may contribute to sensory processing, coordination, and learning challenges. See our detailed guides: primitive reflexes and autism and retained primitive reflexes treatment.
What are primitive reflexes: Automatic involuntary movement patterns present at birth, brainstem-controlled, integrating by 6–12 months. What are the 5 primitive reflexes: Moro, rooting, palmar grasp, ATNR, TLR. List of primitive reflexes: Moro, rooting, sucking, palmar grasp, plantar grasp, ATNR, TLR, STNR, Babinski, stepping, swimming. Types of primitive reflexes: Feeding reflexes, motor/movement reflexes, protective reflexes, postural reflexes. Examples of reflexes in babies / examples of simple reflexes in infants: Moro startle, rooting toward cheek touch, palmar grasp, Babinski toe fan, stepping movements. Brisk reflexes autism: Exaggerated reflex response on neurological exam — part of broader assessment. What are slow reflexes a sign of: Reduced neurological responsiveness.
Is Your Child Showing Signs of Retained Reflexes?
Our free tool helps map your child’s sensory profile — practical information for your occupational therapist.
Free Sensory Profile & Support Tool for Parents →