Newborn reflexes explained

Newborns aren't just tiny humans with limited control. They come pre-programmed with a set of automatic reflexes that protect them, help them feed, and slowly disappear as their brain develops voluntary movement. Knowing what each one does is reassuring (your baby is supposed to do that) and helps you spot real concerns.

Why newborns have primitive reflexes

Primitive reflexes are inherited from very early in human development. They are involuntary motor responses controlled by the brainstem (the most ancient part of the brain). They serve specific survival functions in the first weeks and months:

• Help baby find and take milk (rooting, sucking, swallowing).
• Help baby cling to a caregiver (grasping, Moro).
• Build the foundation for later voluntary movement (stepping, crawling).

As the higher brain develops, it takes over. The primitive reflexes are gradually inhibited and replaced by voluntary movement. Most are gone by 4 to 6 months. A few last longer.

The reflexes you'll see most

Rooting reflex

What it does: When you touch the corner of baby's mouth or cheek, they turn toward the touch and open their mouth, searching for the breast or bottle. Critical for feeding in the first weeks.
Lasts until: 4 months.
Watch for: Total absence at birth can indicate a feeding problem. Bring up at the hospital.

Sucking reflex

What it does: Anything that touches the roof of baby's mouth (finger, nipple, pacifier) triggers a strong suck. Pairs with rooting and swallowing as the basic feeding circuit.
Lasts until: Voluntary sucking takes over around 4 months. Some babies retain a comfort suck reflex longer.
Watch for: Weak suck or inability to coordinate suck-swallow-breathe in a newborn — flag with your pediatrician or lactation consultant.

Moro reflex (startle)

What it does: A sudden change in position, loud sound, or feeling of falling causes baby's arms to fling outward, fingers to spread, then arms to curl back in toward the chest. Often followed by crying. This is what swaddling helps suppress at night.
Lasts until: 4 to 6 months.
Watch for: Absence on both sides, or only on one side (could indicate nerve injury or muscle issue).

Grasp reflex (palmar)

What it does: When you press a finger into baby's palm, they curl their fingers tightly around it. Strong enough that a newborn can almost support their own body weight (do not test this, but it's true).
Lasts until: 5 to 6 months.
Watch for: Total absence on one or both sides.

Plantar grasp

What it does: Same idea, but with the foot. Press your thumb against the ball of baby's foot and their toes curl down.
Lasts until: 9 to 12 months (when baby starts pulling to stand).

Stepping reflex

What it does: Hold baby upright with feet touching a flat surface and they'll make stepping motions, like they're walking. This is not actually walking and has nothing to do with when they will walk.
Lasts until: 2 months.
Watch for: Stepping reflex shouldn't persist past 2 to 3 months. If still strong at 4+ months, mention to pediatrician.

Babinski reflex

What it does: Stroke the sole of baby's foot from heel to toe. Toes fan out, big toe extends upward. (In adults, the opposite is the normal response — toes curl down.)
Lasts until: 1 to 2 years.
Watch for: Persistence well into the toddler years can indicate nervous system issues. Pediatrician will test at well visits.

Tonic neck reflex (fencing)

What it does: When baby turns their head to one side, the arm on that side extends out and the opposite arm bends up at the elbow — like a tiny fencer. Often most visible from about 1 to 4 months.
Lasts until: 5 to 7 months.

Less-known but still normal reflexes

Gag reflex

Triggered when something touches the back of the throat. Lifelong reflex. Very forward in newborns (gets triggered at the front of the tongue) and gradually moves back as baby learns to eat solids. The forward gag is why baby-led weaning works — they can clear food themselves before it actually causes choking.

Galant reflex

Stroking one side of baby's lower back causes them to curve their body toward that side. Lasts until 4 to 6 months. Usually only tested by pediatricians.

Crawling reflex

If you put a newborn on their tummy, they may do tiny crawling motions with their legs. Not real crawling, just primitive movement. Lasts about 6 weeks.

Doll's eye reflex

When you slowly turn baby's head to one side, their eyes lag behind briefly. Lasts about 2 weeks.

Swimming reflex

If a newborn is placed face-down in water, they can hold their breath and make swimming motions. This is real and well-documented. It is also not safety swimming and disappears around 6 months. Never test this without proper supervision.

The 3 things that warrant a call

Most reflexes get checked at every well visit. Things to flag between visits:

1. A reflex is absent on one side

If the grasp, Moro, or rooting reflex is strong on one side but completely absent or much weaker on the other, that asymmetry is worth flagging. Could indicate a birth injury, nerve compression, or muscle issue. Often treatable when caught early.

2. A reflex is much weaker or stronger than expected

Particularly weak suck or rooting reflex can affect feeding. Exaggerated Moro or stiff body tone can indicate other concerns. Mention any concern at well visits.

3. A primitive reflex persists long past its expected window

Reflexes are supposed to fade as voluntary movement takes over. If your 6-month-old is still showing a strong tonic neck reflex or stepping reflex, mention it. Pediatricians and occupational therapists can address persistent primitive reflexes.

What "intact reflexes" means on your discharge summary

Most hospital discharge summaries will mention "neuro intact" or "reflexes intact." This means your pediatrician already tested the main reflexes (Moro, rooting, suck, grasp, stepping) and they were normal. They will check again at each well visit through about 6 months.

Reflexes and tummy time

Some primitive reflexes interfere with later movement if they don't fade on time. For example, persistent tonic neck reflex can make it hard for baby to bring hands to midline (necessary for grasping toys). Tummy time, floor play, and varied positions help reflexes integrate naturally. More on tummy time in our tummy time guide.

When to call your pediatrician

• You don't see a Moro/startle reflex at all in a newborn.
• One side of the body responds differently than the other to the same trigger.
• Sucking is weak and feeding is going poorly.
• A reflex is still present months after it should have faded.
• Baby seems unusually stiff, very floppy, or has unusual movements.
• Hands stay clenched in fists past 3 to 4 months.
• Baby never seems to bring hands to mouth or midline by 3 months.