Learn what the ATNR or “fencing reflex” looks like, why it is normal in young babies, when it usually fades, and which movement patterns are worth discussing with your child's pediatrician.
Home Care Nursing • Nursing Education • Pediatric & Complex Care
Dolores Fishbein, MSN, RN brings years of home care nursing experience together with extensive experience in nursing education. Her background includes supporting children and families in the home, educating nurses and caregivers, and translating clinical information into practical guidance for everyday pediatric care.
Reviewed for clinical accuracy, developmental context, and appropriate family guidance. Last reviewed September 13, 2026.
What is the asymmetric tonic neck reflex?
The asymmetric tonic neck reflex, or ATNR, is a normal primitive reflex seen in young infants. When a baby's head turns to one side, the arm and leg on the side the face is turned toward tend to straighten while the opposite limbs bend. Because the position resembles a fencer, ATNR is also called the “fencing reflex.”
The reflex is expected early in infancy and gradually becomes less prominent as voluntary movement develops. The American Academy of Pediatrics describes the tonic neck reflex as generally disappearing around 5 to 7 months.
What is ATNR in a baby?
ATNR is one of several primitive reflexes that are present early in life. Primitive reflexes are automatic movement patterns controlled by the developing nervous system before a baby has mature voluntary control over posture and movement.
During ATNR, turning the head changes the position of the arms and legs. The limbs on the side toward which the baby's face turns tend to extend, while the opposite limbs tend to flex.
Seeing a fencing-like posture in a newborn does not by itself mean something is wrong. The reflex is expected during early neurological development and becomes less prominent as voluntary control matures.
What does the fencing reflex look like?
Parents may notice the posture when their baby is lying calmly on their back with the head turned toward one side.
Face Turns to One Side
The baby's head turns toward the right or left.
Arm and Leg Extend
The arm and leg on the side the baby is looking toward tend to straighten.
Limbs Flex
The arm and leg on the opposite side tend to bend.
The Baby Is Not Doing It Deliberately
ATNR is an automatic reflex rather than a voluntary movement or learned pose.
Pediatric clinicians can evaluate primitive reflexes as part of a broader neurological and developmental examination. If you are concerned about your baby's movement, symmetry, muscle tone, or milestones, discuss what you are seeing with your child's healthcare professional.
When does the asymmetric tonic neck reflex disappear?
There is some normal variation in the timing reported by clinical references. The American Academy of Pediatrics lists the tonic neck reflex as appearing at birth and generally disappearing between 5 and 7 months.
Other clinical references describe ATNR becoming less prominent earlier in infancy, with variation in the exact integration window. This is one reason a single age cutoff should not be used by itself to diagnose a developmental or neurological condition.
Why is the tonic neck reflex important?
ATNR is part of early neurological development. Clinical references describe the reflex as helping bring an infant's hand into the visual field and contributing to early hand-eye coordination and body awareness.
As the nervous system matures, babies rely less on primitive reflexes and increasingly use purposeful movements such as reaching, bringing the hands together, rolling, sitting, and exploring objects.
Developmental Milestones View CDC Developmental Milestones →When should parents talk with a pediatrician about ATNR?
Parents do not need to diagnose a retained reflex themselves. What matters more is the child's overall movement pattern, developmental progress, symmetry, muscle tone, and whether the reflex appears to interfere with voluntary movement.
The Reflex Looks Different on Each Side
The American Academy of Pediatrics recommends telling your pediatrician when the tonic neck reflex seems different on one side or when the baby appears to move one side of the body better than the other.
The Response Remains Very Strong
A strong or obligatory reflex that remains well beyond the expected infant period may deserve developmental or neurological assessment.
It Seems to Limit Voluntary Movement
Discuss concerns if the movement pattern appears to interfere with bringing the hands together, reaching, rolling, sitting, or other age-appropriate movement.
Other Milestones Are Also a Concern
A reflex is interpreted alongside the child's broader development rather than in isolation.
A retained ATNR is a clinical finding, not a diagnosis by itself.
Persistent primitive reflexes can occur with neurological or motor disorders, but one reflex alone cannot determine the cause. A pediatrician or qualified developmental professional can evaluate the child's complete movement and developmental pattern.
What does retained ATNR mean?
“Retained ATNR” generally means the reflex remains clearly present beyond the age when primitive reflex activity would normally be expected to diminish.
An obligatory persistent ATNR may make symmetrical movement more difficult. Clinical literature describes possible interference with bringing both hands to midline, reaching across the body, rolling, sitting balance, and coordinated movement when the reflex remains strongly expressed.
Does retained ATNR mean a child has cerebral palsy?
No. Persistent primitive reflexes can be seen in children with neurological conditions, including cerebral palsy, but the presence of ATNR alone does not diagnose cerebral palsy or any other condition.
Does ATNR cause ADHD, dyslexia, or learning disabilities?
Parents may find strong claims online connecting retained primitive reflexes with ADHD, dyslexia, handwriting problems, or school performance. Some research has reported associations between retained primitive reflexes and certain motor or attention measures, but association does not establish that ATNR causes those conditions.
ATNR should not be used by itself to diagnose ADHD, dyslexia, a learning disability, or another neurodevelopmental condition.
How is ATNR evaluated?
A healthcare professional may assess primitive reflexes as part of a broader neurological, developmental, or therapy evaluation.
Movement & Symmetry
The clinician may observe spontaneous movement, posture, symmetry, head control, and how the child uses both sides of the body.
Primitive Reflex Responses
Reflexes may be assessed in the context of the child's age and overall neurological examination.
Motor Milestones
Reaching, midline play, rolling, sitting, crawling, and other developmental skills may be reviewed depending on the child's age.
Birth & Medical Context
The child's birth history, medical conditions, muscle tone, developmental history, and family concerns may also help guide the evaluation.
Can physical or occupational therapy help?
Physical or occupational therapy may be recommended when a child has motor, positioning, coordination, strength, mobility, fine-motor, or functional-development needs.
Therapy should focus on the child's functional needs and developmental goals rather than assuming that every retained reflex needs a specific “reflex integration” program.
A pediatrician, physical therapist, occupational therapist, neurologist, developmental specialist, or other qualified clinician can determine whether additional evaluation or therapy is appropriate based on the child's overall development.
What can parents watch for at home?
Rather than repeatedly trying to trigger the reflex, parents can pay attention to everyday movement and developmental progress.
Symmetrical Movement
Notice whether your baby appears to move both sides of the body in a reasonably similar way during normal activity.
Hands Coming Together
As voluntary control develops, babies increasingly bring their hands toward the middle of the body and explore objects.
Purposeful Arm Movement
Watch for gradual progression from automatic movements toward intentional reaching and grasping.
Overall Development
Track development across movement, communication, play, learning, and social interaction rather than focusing on one reflex alone.
Asymmetric tonic neck reflex FAQs
What is the asymmetric tonic neck reflex?
ATNR is a primitive infant reflex in which turning the head toward one side causes the arm and leg on the face side to tend to extend while the opposite limbs tend to flex.
Why is ATNR called the fencing reflex?
The position resembles a fencing stance, with one arm extending toward the direction the baby is looking and the opposite arm bending.
Is the fencing reflex normal in babies?
Yes. ATNR is an expected primitive reflex in young infants and normally becomes less prominent as voluntary movement develops.
When should the ATNR disappear?
The American Academy of Pediatrics lists the tonic neck reflex as generally disappearing between 5 and 7 months. Other clinical references describe some variation in the exact timing.
What does retained ATNR mean?
Retained ATNR means the reflex remains clearly present beyond the period when it would normally diminish. A persistent reflex should be interpreted together with movement, symmetry, muscle tone, developmental milestones, and the child's medical history.
Should I be concerned if my baby's reflex looks different on one side?
The American Academy of Pediatrics advises parents to tell their pediatrician when the tonic neck reflex appears different on one side or when a baby seems to move one side of the body better than the other.
Does retained ATNR mean cerebral palsy?
No. Persistent primitive reflexes can occur with neurological conditions, but ATNR by itself cannot diagnose cerebral palsy or another neurological disorder.
Can retained ATNR cause ADHD or dyslexia?
Some studies have reported associations between retained primitive reflexes and certain developmental or attention measures, but these findings do not establish that ATNR causes ADHD, dyslexia, or a learning disability.
Can occupational or physical therapy help a child with retained ATNR?
Therapy may help children who have identified movement, coordination, positioning, fine-motor, gross-motor, or other functional needs. Whether therapy is appropriate should be determined through an individualized professional evaluation.
This article provides general educational information and does not diagnose retained primitive reflexes, developmental delay, cerebral palsy, ADHD, learning disorders, or other medical conditions. If you have concerns about your child's movement, muscle tone, symmetry, reflexes, development, or loss of previously acquired skills, contact your child's pediatrician or another qualified healthcare professional.
