Retained primitive reflexes are automatic movement patterns from infancy that remain active in the brain and body past the age when they should have naturally faded. These reflexes serve critical survival functions in newborns, but the brain is supposed to suppress them within the first year of life as voluntary motor control takes over. When that process stalls, the lingering reflexes can quietly interfere with coordination, attention, emotional regulation, and learning well into childhood and sometimes adulthood.
How Primitive Reflexes Work in Infants
Every baby is born with a set of involuntary movement responses controlled by the brainstem. These reflexes help newborns survive before the higher brain has developed enough to manage voluntary movement. The rooting reflex turns a baby’s head toward a touch on the cheek to find food. The palmar grasp makes a baby clench anything placed in the palm. The Moro reflex flings a baby’s arms outward in response to a sudden change in position, functioning as an infant alarm system.
As the brain matures, the cortex gradually takes control and inhibits these automatic responses, typically between 4 and 6 months of age for most early reflexes. Some, like the symmetrical tonic neck reflex (STNR), integrate a bit later. This process is called integration: the reflex doesn’t disappear entirely, but the brain layers more sophisticated, voluntary movement patterns on top of it. Crawling, reaching, sitting upright, and eventually walking all depend on these earlier reflexes being properly integrated so they no longer fire automatically.
Why Some Reflexes Don’t Integrate
Several factors can disrupt or delay the integration process. Cesarean section delivery, birth trauma, exposure to toxins or certain medications during pregnancy, and the use of anesthetics during birth have all been identified as risk factors. But it’s not only birth-related events that matter. Decreased tummy time during infancy, limited or skipped crawling, early walking (which can bypass the crawling phase the brain needs for integration), head injuries, and chronic ear infections can all contribute to reflexes staying active longer than they should.
The common thread is that something interrupted the normal sequence of movement experiences the developing brain relies on. A baby who spends very little time on the floor, for example, misses repetitive movement patterns that help the cortex practice overriding brainstem-driven reflexes. The result is a nervous system that still defaults to automatic responses in situations where voluntary, coordinated movement should have taken over.
The Moro Reflex and Emotional Reactivity
The Moro reflex is a baby’s primitive fight-or-flight reaction. It’s normally replaced by the adult startle reflex by about four months of age. When it persists beyond that window, the nervous system remains stuck in a heightened state of alert, reacting to ordinary sensory input as though it were a threat.
Children with a retained Moro reflex often become oversensitive and overreactive to sensory stimulation. This can look like poor impulse control, sensory overload in noisy or busy environments, anxiety, emotional immaturity, and mood swings that seem disproportionate to the situation. Motion sickness, poor balance, poor coordination, difficulty adapting to change, and being easily distracted are also common signs. For a parent watching this play out, it can look like a behavioral issue when the underlying cause is neurological. The child’s brainstem is essentially hitting an alarm button that should have been decommissioned in infancy.
The ATNR and Struggles With Reading and Writing
The asymmetrical tonic neck reflex (ATNR) is the “fencing” reflex. When a newborn turns their head to one side, the arm and leg on that side extend while the opposite arm and leg bend. It plays a role in developing hand-eye coordination early on, but it needs to integrate for a child to use both sides of their body independently.
When the ATNR stays active, turning the head still triggers involuntary arm and leg movements, even if they’re subtle. This creates real problems in a classroom. Eye tracking, the smooth left-to-right movement needed for reading, becomes difficult because head movement keeps disrupting hand and arm position. Writing across a page is affected too, since crossing the body’s midline (moving the hand from one side of a page to the other) requires the exact independence of head and limb movement that a retained ATNR undermines. Children with this pattern often have messy handwriting, lose their place while reading, or avoid tasks that require sustained visual tracking.
The STNR and Sitting Still
The symmetrical tonic neck reflex links head position to arm and leg movement in a different way. When a baby looks up, their arms straighten and their legs bend. When they look down, their arms bend and their legs straighten. This reflex helps babies transition from lying on their stomach to getting up on all fours, and it’s a building block for crawling.
When it stays active past early development, bending or lifting the head still causes automatic movements in the arms and legs. This interferes with any activity requiring good posture, coordination, and body control. Sitting upright at a desk becomes genuinely difficult: looking down at a worksheet can cause the arms to bend and the legs to stiffen, making the child slump, fidget, or wrap their legs around the chair for stability. Some children adopt a W-sitting position on the floor because it locks the hips in place and compensates for the lack of postural control. These kids aren’t choosing to slouch or wiggle. Their nervous system is making it physically hard to sit still and look at their work at the same time.
How Retained Reflexes Are Identified
Testing for retained primitive reflexes is straightforward and noninvasive. A trained occupational therapist, developmental optometrist, or pediatric physical therapist will move the child through specific positions that should trigger each reflex in an infant but produce no response in an older child. If the reflex fires, even partially, it’s considered retained. The evaluation typically covers several reflexes at once, since children rarely retain just one in isolation.
The signs that prompt parents to seek testing usually aren’t the reflexes themselves but the downstream effects: a child who is bright but struggles with reading, has unexplained anxiety, can’t sit still, has poor handwriting, or seems clumsy despite no obvious physical cause. These patterns overlap significantly with ADHD, sensory processing disorder, and learning disabilities, which is why retained reflexes often go unrecognized. They can coexist with these diagnoses or mimic them.
Integration Exercises and What to Expect
The good news is that the brain retains the ability to integrate these reflexes well beyond infancy. Targeted, repetitive movement exercises can train the cortex to override the brainstem patterns that should have been suppressed years earlier. These exercises are simple and designed to replicate the developmental movements the child missed.
A Moro reflex integration exercise, for example, involves sitting down, tilting the head slightly back while opening the arms and legs outward, then leaning forward, crossing the right arm and leg over the left while looking down. The movement is then repeated with the left side crossing over the right. This open-and-close pattern mimics the reflex itself in a controlled, rhythmic way, giving the brain repeated opportunities to practice suppressing the automatic response.
Programs typically involve 5 to 15 minutes of daily exercises done consistently over several months. Progress isn’t instant. Most families notice gradual shifts: a child who tolerates noise better, sits more comfortably, reads with less effort, or has fewer emotional meltdowns. The timeline varies depending on how many reflexes are retained and how consistently the exercises are performed, but meaningful changes often emerge within 8 to 12 weeks of daily practice.
Occupational therapists and other specialists can design a program tailored to a child’s specific retained reflexes. Some families work with a practitioner weekly and do exercises at home between sessions, while others follow structured home programs after an initial evaluation. Floor-based play, crawling games, and activities that encourage crossing the midline also support integration as part of everyday life.