Missing Primitive Reflexes in Newborns
The short answer
Primitive reflexes (Moro, rooting, sucking, grasp, stepping) are expected in all healthy newborns and are tested as part of the newborn neurological exam. Absent or significantly diminished reflexes may indicate a neurological concern, prematurity-related immaturity, or the effects of medication and should be evaluated by your pediatrician.
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By Age
What to expect by age
Newborns are expected to have several primitive reflexes that demonstrate normal brain and nervous system function. These include the Moro reflex (startle), rooting (turning head toward touch on cheek), sucking, palmar grasp (gripping finger), and stepping reflex. Your pediatrician tests these at birth and at well-child visits. Absent or very weak reflexes can be caused by prematurity, birth injury, exposure to medications or substances, infection, or neurological conditions. Some variation in reflex strength is normal, but complete absence of reflexes warrants further evaluation.
Primitive reflexes should still be present during this period. As the brain matures, these reflexes begin to integrate (fade) gradually. The stepping reflex fades first, usually by 2 months. The others persist through this period. If reflexes that should be present are absent, your pediatrician may recommend neurological evaluation.
Primitive reflexes normally begin to fade during this period as voluntary movements replace them. The Moro reflex typically fades by 4-6 months, and the palmar grasp integrates as voluntary grasping develops. Reflexes that persist too long (beyond their expected time frame) can also be a concern.
Most primitive reflexes should have integrated by this age. Persistent primitive reflexes beyond their normal time frame may indicate neurological issues and should be evaluated. Conversely, the protective reflexes (such as the parachute reflex) should be developing.
What Should You Do?
When to take action
- All primitive reflexes present at birth and during the newborn period
- Gradual fading of reflexes at the expected developmental time points
- Slight variation in reflex strength that does not affect function
- One or more reflexes seem weaker than expected
- Your baby does not root, suck, or grasp as strongly as expected
- Reflexes seem to persist longer than expected or are not fading on schedule
- Complete absence of primitive reflexes in a newborn, which may indicate significant neurological depression or injury
- A floppy, unresponsive baby with absent reflexes and poor feeding, which requires urgent medical evaluation
Sources
Related Resources
Trust your instincts. If something feels wrong, reach out to your pediatrician.
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Related Medical Concerns
Weak Rooting Reflex in Newborns
A weak rooting reflex (where baby turns toward a touch on the cheek to find the breast or bottle) can sometimes contribute to feeding difficulties in newborns. It may be caused by prematurity, sleepiness, recent feeding, illness, or neurological factors. Most babies develop a stronger rooting reflex with time and feeding practice, but persistent weakness should be evaluated.
My Baby Seems Floppy (Hypotonia)
A "floppy" baby is one whose muscles feel unusually relaxed and who may slip through your hands when you lift them under the arms. Many cases of mild floppiness improve on their own as your baby grows stronger, but it is important to have your pediatrician evaluate your baby to rule out any underlying conditions.
Excessive Moro (Startle) Reflex in Newborns
The Moro (startle) reflex is a normal primitive reflex present in all newborns. Some babies seem to have a more active or sensitive startle reflex, which can cause them to wake frequently during sleep. This is a normal variation and typically diminishes by 3-4 months of age. Swaddling can help reduce the impact of the Moro reflex on sleep.
My Baby's Head Shape Looks Abnormal
Many babies develop temporary head shape irregularities that are completely normal. A cone-shaped head from vaginal delivery reshapes within days. Mild positional flattening (plagiocephaly) from sleeping on the back is very common and usually improves with repositioning and tummy time. However, head shape changes involving ridges, a persistently bulging fontanelle, or rapid head growth changes should be evaluated to rule out craniosynostosis.
Achondroplasia (Dwarfism) in Babies
Achondroplasia is the most common form of short-limbed dwarfism, affecting about 1 in 15,000 to 40,000 births. It is caused by a mutation in the FGFR3 gene and is usually apparent at birth with characteristic features including short limbs, a larger head, and a prominent forehead. Intelligence is normal. With monitoring for specific complications and supportive care, children with achondroplasia lead full, active, and independent lives.
Adenoid Hypertrophy and Breathing
Adenoids are lymphoid tissue located behind the nose that help fight infection in young children. When adenoids become enlarged (adenoid hypertrophy), they can block the nasal airway, causing chronic mouth breathing, snoring, nasal speech, and sleep-disordered breathing. Enlarged adenoids are most common between ages 2-7 and are a leading cause of obstructive sleep apnea in young children. Treatment ranges from watchful waiting and nasal steroids to surgical removal (adenoidectomy) if breathing or sleep is significantly affected.