Primitive reflexes are involuntary movements that originate in the brainstem and are present in all healthy newborns. They exist to help a baby survive the first months of life, handling tasks like feeding and reacting to danger before the brain is mature enough to control movement voluntarily. As the higher regions of the brain develop, they suppress these reflexes, typically by 4 to 6 months of age, replacing them with intentional, controlled movement. If these reflexes persist beyond their expected window, or if they reappear later in life, it can signal a neurological problem worth investigating.
Why Babies Have Them
A newborn’s brain is remarkably underdeveloped at birth. The brainstem, the most basic part of the nervous system, is functional, but the cortex (the outer brain responsible for thinking and deliberate action) is still wiring itself together. Primitive reflexes bridge that gap. They are pre-programmed motor responses that let a baby do essential things like latch onto a breast, grip a caregiver’s finger, or startle in response to a sudden change, all without any conscious effort.
As the cortex matures over the first several months, it gradually takes over. The brain essentially says “I’ve got this now” and inhibits the brainstem-driven reflexes. This handoff from automatic to voluntary movement is one of the key markers pediatricians track during early development.
The Major Primitive Reflexes
Rooting and Sucking Reflexes
These are the feeding reflexes. The rooting reflex causes a baby to turn toward anything that touches their cheek or the corner of their mouth, helping them find a nipple. It appears around 28 weeks of gestation and typically fades by 4 to 6 months. The sucking reflex, which develops between 30 and 35 weeks of gestation, coordinates the complex task of sucking, swallowing, and breathing at the same time. During swallowing, the airway closes briefly to prevent milk from entering the lungs. Without these two reflexes working in tandem, a newborn simply couldn’t eat.
Moro (Startle) Reflex
The Moro reflex is a baby’s alarm system. When an infant experiences a sudden loss of support or a loud noise, the arms fling outward with fingers spread wide and the back arches slightly. Then, almost immediately, the arms pull back in toward the body. Pediatricians test it by gently lifting a baby’s arms and releasing them, simulating the sensation of falling. It’s the suddenness that triggers the response, not the distance of the drop.
This reflex can be detected as early as 25 weeks of gestation and is reliably present by 30 weeks. It starts fading around 12 weeks after birth and is typically gone by 6 months. Parents often notice it when a baby startles during sleep, arms jerking outward in response to a noise or a shift in position.
Asymmetric Tonic Neck Reflex (ATNR)
When you turn a newborn’s head to one side, the arm and leg on that side extend while the opposite arm and leg flex. It looks a bit like a fencing pose. This reflex appears around 18 weeks in utero, is most prominent between 1 and 4 months of age, and disappears somewhere between 3 and 9 months. It plays a foundational role in developing postural stability, eye tracking, and the ability to coordinate movements across the midline of the body, skills that later become critical for things like reading and writing.
Palmar Grasp Reflex
Place a finger in a newborn’s palm and they’ll grip it tightly. This is the palmar grasp reflex, and it’s surprisingly strong. It’s present at birth and gradually fades as the baby develops the ability to voluntarily reach for and release objects. Its integration is important for fine motor development, since a child needs to let go of the automatic grip before they can learn to use their hands with precision.
Babinski Reflex
When you stroke the sole of a baby’s foot from heel to toe, the big toe fans upward and the other toes spread apart. This is a normal finding in infants and children up to about 2 years old, though it can disappear as early as 12 months. In adults, this same response is abnormal and often points to damage in the brain or spinal cord. It’s one of the most well-known neurological signs tested during physical exams at any age.
Galant Reflex
Stroking along one side of a baby’s spine causes the body to curve toward the stimulus, swinging the hip on that side outward. This spinal reflex begins developing around 20 weeks of gestation and integrates within the first 9 months after birth. It’s thought to play a role in the birthing process and in early movement patterns.
What Happens When Reflexes Don’t Fade
When primitive reflexes persist beyond their expected timeline, it’s called “retained primitive reflexes,” and it suggests the higher brain hasn’t fully taken over motor control. This can show up in a range of ways depending on which reflexes remain active.
A retained ATNR, for instance, can interfere with hand-eye coordination and fine motor tasks like handwriting, because the reflex links head position to arm movement in ways that disrupt controlled, deliberate motion. Retained reflexes more broadly have been associated with clumsiness, poor posture, awkward gait, difficulty with balance, and trouble with coordination. Research has documented links between retained primitive reflexes and learning difficulties, including lower scores on attention and concentration tests in preschool-aged children and poorer early academic performance.
Retained reflexes appear more frequently in children with ADHD and autism spectrum disorder. The connection runs in both directions: the reflexes may contribute to motor and cognitive challenges, and the underlying neurological differences that produce these conditions may also prevent reflexes from integrating on schedule. Studies have found that children with retained reflexes often have a limited range of skilled movements and gestures, which can affect both physical coordination and social communication.
Reflexes Returning in Adults
Primitive reflexes can also reappear after being absent for decades. When they do, neurologists call them “frontal release signs” because they typically indicate damage to the frontal lobes of the brain. Conditions that can bring them back include dementia, Parkinson’s disease, traumatic brain injury, and metabolic disorders affecting the brain.
The grasp reflex returning in an adult is a fairly specific indicator of damage to the supplementary motor area in the frontal lobe. Other reflexes, like the sucking and palmomental reflexes, are less specific. One study found the palmomental reflex in 11% of healthy adults but in 72% of adults with neurological disease. So finding one of these reflexes in an adult doesn’t automatically mean something is wrong, but it raises the index of suspicion, especially if multiple reflexes are present or other neurological symptoms exist.
How Retained Reflexes Are Addressed
For children with retained primitive reflexes, several therapeutic approaches focus on helping the brain complete the integration process it didn’t finish on its own. Programs like the Primary Movement Program and protocols from the Institute for Neuro-Physiological Psychology use specific sequences of rhythmic, whole-body movements designed to stimulate the vestibular system (your sense of balance) and proprioceptive pathways (your sense of where your body is in space). These are the same sensory systems that drive reflex integration during normal infant development.
The exercises typically involve slow, repetitive movements that mimic the developmental patterns babies go through naturally, like rolling, crawling, and weight-shifting. A 12-week structured exercise program targeting reflex integration in children with ADHD and autism showed promise in improving not just motor coordination but also social engagement, attention, and behavioral regulation. Research by Sally Goddard Blythe, focused on children between 7 and 9 years old, supports the case that early intervention targeting coordination and balance can improve both cognitive and motor outcomes when neurological immaturity is contributing to delays.
Occupational therapists and developmental specialists are the most common providers offering reflex integration work. The process generally takes months of consistent practice rather than weeks, and the exercises are simple enough that families usually do them at home between therapy sessions.