Sensory processing
The ATNR: The Fencing Reflex, and What It Means When It Stays
Turn a newborn's head and one arm extends while the other bends. Why that happens, when it should stop, and what an obligatory response blocks.
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The asymmetric tonic neck reflex — the ATNR, or the “fencing position” — is what happens when a calm newborn lying on their back has their head turned to one side: the arm and leg on the side the face is turned toward extend, and the opposite arm and leg bend. It appears around 35 weeks of gestation and typically integrates by 3 to 4 months.1 It has a job while it lasts: it brings the hand into the infant's visual field as the head turns, which supports early hand-eye coordination.1 The distinction that matters clinically is between an OBLIGATORY response, where the limbs lock into the position and stay, and a facultative one, where the tendency is there but can be overcome. An obligatory ATNR persisting past 4 to 6 months is the one with documented consequences.
What is the ATNR (asymmetric tonic neck reflex)?
The ATNR is a newborn reflex in which turning the head to one side straightens the arm and leg on the side the face turns toward and bends the arm and leg on the other side. The clinical reference classes it, with the Moro, as a protective reflex.1
Turn a calm, supine newborn’s head to one side and a predictable thing happens: the arm and leg on the side the face is turned toward extend, and the arm and leg on the other side bend. The posture looks like a fencer’s stance, which is where the common name comes from.1
What it is for. The ATNR brings the hand into the infant’s visual field as the head turns, which supports the development of hand-eye coordination. It also promotes sensory awareness of body laterality, and may support the cross-lateral movement patterns needed for crawling.1
Why is it called the fencing reflex?
Because the posture looks like a fencer’s stance: face turned toward one outstretched arm, the other arm and leg bent. The clinical reference calls it the “fencing position”.1
Parents usually notice it without being told what it is: a baby lying on their back, head turned, one arm reaching out, gazing toward that hand. That is the point of it. The outstretched hand lands in the baby’s line of sight, and looking at it is the beginning of hand-eye coordination.1 Seeing the fencer position in a young baby is expected, not a warning sign.
When does the ATNR appear, and when does it go away?
It appears around 35 weeks of gestation and typically integrates by 3 to 4 months of age.1
| Point | What is expected1 |
|---|---|
| Around 35 weeks of gestation | The reflex appears. |
| By 3 to 4 months of age | Typically integrates. |
| Beyond 4 to 6 months | An obligatory response at this point has documented consequences for motor development. |
The skills an obligatory ATNR gets in the way of are early ones on CDC’s checklists: by 4 months most babies bring their hands to their mouth, and by 6 months they roll from tummy to back.8
How does a clinician check the ATNR?
The clinician turns the baby’s head to each side in turn and watches what the arms and legs do, and whether the posture can be broken. The infant is supine and calm. The examiner gently rotates the head to one side and holds it there for 10 to 15 seconds, then repeats to the other side — both sides are tested, because asymmetry between them is itself information.1
Obligatory or facultative. This is the distinction that changes what the finding means. In an obligatory response the limbs assume the position and remain fixed there. In a facultative one the tendency is present but can be overcome.1 The documented consequences below attach to the obligatory kind.
What does an obligatory or persistent ATNR mean?
An obligatory ATNR persisting beyond 4 to 6 months stops an infant from holding a symmetric posture, and the consequences are specific and sequential.1
What it blocks
- Bringing both hands to the midline — a prerequisite for two-handed play
- Reaching across the body to grasp
- Rolling, and then sitting and crawling, which build on symmetric posture
What it can point to. A persistent ATNR is strongly associated with cerebral palsy, particularly spastic quadriplegia and hemiplegia, where it often stays obligatory well beyond infancy. Children with autism also show higher rates of a persistent ATNR.1 Absence matters less than with some reflexes: an absent ATNR in a newborn is less alarming than an absent Moro, although a complete absence alongside other absent or abnormal reflexes suggests diffuse neurological dysfunction.1
Where this stops. This is a documented consequence of an obligatory response in infancy, not a general claim about school-age difficulty. A retained reflex does not automatically mean impairment,2 and the broader association between retained reflexes and later academic performance is correlational. A 2026 systematic review of 14 studies in children aged 3 to 11 without neurodevelopmental diagnoses found consistent negative associations with motor outcomes and with reading, spelling and mathematics, and concluded that the available evidence “remains limited and heterogeneous”.3
ATNR vs STNR: what is the difference?
The ATNR responds to turning the head to one side and makes the two sides of the body do opposite things; the STNR is assessed with the head bent forward and back, and both sides respond alike.1,7 They are often named together because both are counted among the reflexes most often still active in school-age children.3
| ATNR | STNR | |
|---|---|---|
| What the head does | Turns to one side1 | Bends forward or back; rated in flexion and in extension7 |
| Window in the standard reference | Appears around 35 weeks of gestation; integrates by 3 to 4 months1 | None given; named only as one of seven dimensions in an assessment scale1 |
| Among the three most often still active at ages 3 to 11 | Yes3 | Yes3 |
| Correlation with ADHD in a meta-analysis of 229 children | r = 0.484 | r = 0.394 |
A correlation of that size is a moderate association across a group. It is not a test for ADHD, and the meta-analysis authors themselves call for longitudinal or experimental studies before cause is claimed in either direction.4 The STNR has its own page, as does the TLR, the third of the trio.
Do ATNR exercises work for handwriting or reading?
That has not been shown. A 2000 trial found that a movement program lowered ATNR scores in children with reading difficulties,5 and a 2026 review found that most of five intervention studies reported better outcomes, while judging the evidence as a whole limited and heterogeneous.3
The 2000 trial is the one most often quoted. Sixty children aged 8 to 11 with reading difficulties and a persistent ATNR were matched into three groups; only the group given a specific movement sequence showed a significant fall in ATNR levels, against a placebo-movement group and a no-movement group.5 Its headline result is a change in the reflex score. Occupational therapy’s professional body is clear that a program should be tied to an everyday outcome rather than to the reflex, and that a retained reflex does not necessarily mean a functional problem.2
If handwriting is the concern, international guidance on children with coordination difficulties suggests practicing handwriting itself, with ways for the child to judge their own work, and teaching keyboarding early alongside it.6 Our pages on dysgraphia and crossing the midline cover what an assessment looks at.
What if I have been told my child has a retained ATNR?
An obligatory ATNR in an infant who is not reaching midline is a reason to see a doctor or a pediatric therapist, and soon. A facultative one in a school-age child is a different conversation, and the questions worth asking are on the parent article.
Start with the questions in the parent article: what everyday difficulty the plan targets, how it was measured, and how progress will be checked. A pediatric occupational therapist can assess handwriting and two-handed skills directly; you can find one near you.
Frequently Asked Questions
What is the fencing reflex?
It is the common name for the asymmetric tonic neck reflex, or ATNR. When a calm newborn's head is turned to one side, the arm and leg on that side extend and the opposite arm and leg bend, producing a posture that looks like a fencer's stance.
When should the ATNR go away?
It appears around 35 weeks of gestation and typically integrates by 3 to 4 months of age.
What is the difference between an obligatory and a facultative ATNR?
In an obligatory response the limbs assume the position and stay locked in it. In a facultative response the tendency is there but can be overcome. The documented consequences for motor development attach to the obligatory kind.
Does a retained ATNR cause handwriting problems?
Retained reflexes have been associated with handwriting difficulty in group studies, but association in a group does not establish cause in an individual child, and occupational therapy guidance states that a retained reflex does not automatically mean impairment.
Is the fencer position normal in a baby?
Yes, in a young baby. The fencer position is the ATNR, which appears around 35 weeks of gestation and typically integrates by 3 to 4 months. A posture that locks in place, or still dominates after 4 to 6 months, is worth showing your baby's doctor.
What is the difference between the ATNR and the STNR?
The ATNR is triggered by turning the head to one side, and the two sides of the body respond differently. The STNR is assessed with the head bent forward and back, and both sides respond the same way. The standard clinical reference gives the ATNR an integration window of 3 to 4 months and gives the STNR none.
Sources
- Chamarthi VS, Gunasekaran V, Daley SF. Primitive Reflexes: Comprehensive Neurological Assessment Across the Lifespan. In: StatPearls. StatPearls Publishing; updated 2026. ncbi.nlm.nih.gov/books/NBK554606 (PMID 32119493). Checked August 25, 2026.
- American Occupational Therapy Association. Don’t use reflex integration programs for individuals with delayed primary motor reflexes without clear links to occupational outcomes. Recommendation AOTA8, Choosing Wisely clinician list, July 27, 2021. archived recommendation. Checked October 5, 2026.
- Provazník A, Musálek M, Bob P, Větrovský T, Malambo C, Silva AF, Anderson D. Persisting primitive reflexes and motor and cognitive development in children: a systematic review. Acta Psychologica. 2026;266:106915. doi:10.1016/j.actpsy.2026.106915 (PMID 42061063).
- Wang M, Yu J, Kim HD, Cruz AB. Attention deficit hyperactivity disorder is associated with (a)symmetric tonic neck primitive reflexes: a systematic review and meta-analysis. Frontiers in Psychiatry. 2023;14:1175974. doi:10.3389/fpsyt.2023.1175974 (PMID 37484683).
- McPhillips M, Hepper PG, Mulhern G. Effects of replicating primary-reflex movements on specific reading difficulties in children: a randomised, double-blind, controlled trial. The Lancet. 2000;355(9203):537–541. doi:10.1016/S0140-6736(99)02179-0 (PMID 10683004).
- Blank R, Barnett AL, Cairney J, et al. International clinical practice recommendations on the definition, diagnosis, assessment, intervention, and psychosocial aspects of developmental coordination disorder. Developmental Medicine & Child Neurology. 2019;61(3):242–285. doi:10.1111/dmcn.14132 (PMID 30671947)
- Bijle MA, Malawade M. Effectiveness of reflex integration exercises on sensory-motor outcomes in children with autism spectrum disorder: a quasi-experimental study. Cureus. 2026;18(7):e111970. doi:10.7759/cureus.111970 (PMID 42544248).
- Centers for Disease Control and Prevention. CDC’s Developmental Milestones (Learn the Signs. Act Early.), milestone pages for 2 months to 5 years. cdc.gov/act-early/milestones. Checked October 5, 2026.
Medical disclaimer. This page is for general educational purposes and does not constitute medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider about your child. Sensory and motor concerns are best assessed by an occupational or physical therapist who can evaluate your individual child.