Moro Reflex in babies: What is it and why it happens


This article will explain why parents find it hard to make a baby sleep.

When an infant monkey is about to fall, it wakes up immediately and tries to grab on to something. A fall from a tall tree-top would be fatal. 

Falling from a tree is fatal for baby monkeys.

In a land far away, an infant monkey falls off a tree while singing Tom Petty’s cult song on its way down.

This life-saving involuntary response that keeps them from falling off treetops is called the Moro reflex. 

What’s this got to do with your baby? Well, everything. 

The Moro reflex is why it’s so hard to transfer your sleeping baby to the crib.  

Moro reflex in babies

While our babies don’t sleep on treetops anymore, they still think they do. When you transfer your baby from your arms to the crib, she feels like she’s about to fall. That ‘fallin’ feeling triggers the moro reflex, waking them up immediately.

Baby wakes up crying when placed in the crib.

In nurseries on this side of the world, an infant of our species exhibits startlingly similar behavior.

Soothing your baby to sleep is half the battle. The other half is transferring the baby to the crib or bassinet when they have fallen asleep on your lap while feeding!

And this time, your fight is against gravity.

When you lift your baby from your lap and lower her into the crib, she perceives a change in acceleration. This change might end up waking the baby!

Ever wondered why your baby is so sensitive to gravity? Like so many other early movements, this isn’t under your cutie’s control either. It’s an automatic response triggered due to the feeling of falling. 

Moro Reflex is this involuntary protective motor response against sudden change of body balance or sudden stimulation. The reflex makes sense considering our evolutionary roots as primates.

The infant feels like she’s falling. She also extends her arms to try to grab on to safety, similar to an infant monkey falling from a tall treetop. 

Moro reflex is one of the crucial reflexes. Its absence after birth or beyond six months is attributed to neurodevelopmental abnormalities. Your baby’s doctor will check for this reflex immediately after birth and during follow-up visits. 

Newborn Moro reflex while sleeping

When a baby exhibits the Moro reflex, their body tenses, their arms abruptly extend upwards and outwards, and their knees pull up sharply. This reflex starts to diminish around the age of three to four months and typically vanishes entirely by the six-month mark.


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Why is Moro reflex important?

The reflex is automatic. It’s in response to a stimulus that bypasses conscious thought.

Knee jerk reflexes, like all reflexes, bypass conscious thought.

It’s perfectly normal. You don’t even need to think about it.

Reflexes are involuntary stimulus-response behaviors of the human nervous system. They do not route to the brain, so the reaction is almost instantaneous. 

Evolutionary biologists consider reflexes to be built-in mechanisms. These mechanisms sustain life, allow humans to react to threats, and sometimes respond without thinking. 

For example, there’s the rooting reflex. Stroke a baby’s cheek, and the head turns to that side, the mouth opens, and the baby attempts to suck your finger. This reflex is essential because it facilitates feeding.

So now you get why your baby instantaneously throws her hands out and wakes up when you lower her in the crib. 


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How to test Moro reflex

You would have seen the doctor pull the infant’s arms while examining and letting them go, causing the sensation of falling. This sudden change in balance causes the reflex and not the distance of the drop.

Moro reflex wakes up a sleeping baby

Moro reflex in a baby: “Quick, Grab on to something.”

The complete Moro reflex involves the following:

  1. Quick opening of both the arms and extension of the forearms
  2. Full opening of the hands
  3. Finally, a smooth and slow return of the hands toward the center of the body. It’s also sometimes accompanied by curling of the fingers. 

Startle reflex vs Moro reflex

The startle reflex is similar to the Moro reflex, with a few differences. The hands don’t open or extend fully in the startle reflex. A sudden noise or movement may also evoke the reflex.

What is the Tonic Neck Reflex (Fencing Reflex)?

The Tonic Neck Reflex, also known as the Fencing Reflex, is a primitive reflex observed in infants. When the infant’s head is turned to one side, the arm on that side extends, while the opposite arm flexes. This reflex usually disappears by the age of 6 months as more voluntary control over movements develops.

When does the Moro reflex end?

You can notice the Moro reflex as early as 25 weeks after conception. It’s usually present by 30 weeks after conception.

The reflex is present in full-term infants. It begins to disappear around 12 weeks and disappears entirely by six months.

As your baby’s nervous system matures, babies exhibit reflexive behaviors different from older children and adults.

These infant reflexes are building blocks for voluntary motor behaviors that develop with experience and maturity of the brain.

Moro reflex is present in full term babies at birth.

Reflexes, although vestigial, indicate progress of a baby’s nervous system and motor skills development.

Thus reflexes indicate neurological development. They also change as the nervous system matures. 

What is asymmetric Moro Reflex?

Injuries during birthing, brain malformation, and muscle weakness can sometimes cause the absence or early disappearance of the Moro reflex.

Asymmetrical Moro causes inhibition of the reflex on the affected side. This can be due to a local injury during birth. It can also be caused by damage to the peripheral nerve, cervical cord, or a collarbone fracture.

Prolonged retention of the reflex beyond six to nine months can delay motor development. You should consult a pediatrician in this case. 

What triggers the Moro Reflex?

When you transfer your baby from your arms to the crib, they experience the feeling that they’re about to fall. That ‘fallin’ feeling triggers the Moro reflex, waking them up immediately.

If your baby has the reflex, it’s a great sign. It shows that their neural development is on track.

However, there isn’t a way to prevent the reflex from occurring. Parents still struggle with making a baby sleep, as it may wake your baby up. 

Changes in sensory information trigger Moro reflex

Babies are sensitive to changes.

Any sudden changes in sensory information trigger the reflex. Here are some common triggers of the reflex:

  1. A sudden loud noise. That accidental creaking sound of the wooden floor just after you place your baby in the crib, for example. 
  2. A sudden touch.
  3. An abrupt change in light intensity. Especially in the blue wavelength.
  4. A sudden change in balance. For example, a drop in altitude (when placed in a crib).
  5. A quick change in the orientation of the baby’s body.
  6. These may not seem like much to you as an adult. However, these are all significant changes to your baby. That’s because your baby’s senses are developing and highly sensitive.

How to reduce the startle reflex and soothe a baby?

Here are some things you can do to reduce startling your baby.

Swaddling and soothing a baby

“Of course, it is happening inside your head, Harry, but why on earth should that mean that it is not real?” Dumbledore might well have been talking about the Moro reflex.

  • Try drawing your baby’s outstretched arms and legs closer to their bodies. Then hold them in place till they calm down.
  • When placing the baby in the crib, lower them very slowly. Avoid making any sudden or jerky motions while they are in your arms. Remember, the suddenness of the movement and not the distance of the drop invokes the Moro reflex.
  • Sway the baby gently while you lower the baby into the crib. The swaying motion can absorb any small jerks that could happen while you are transferring. This trick can help keep your baby asleep while moving them into the crib.
  • Hold the baby in front of you ‘Kangaroo-style. Apart from a sense of security, your baby can smell you, hear you, and feel your warmth in this position.
  • Always place the baby closer to your body with their arms held close to the center of their body. Alternatively, cross their arms and put them on their stomach against your body. This position stabilizes your baby even while you walk.
  • Use a swaddle. It restricts the baby’s movements and helps draw their extended limbs back. Swaddling also simulates the womb environment, which can help soothe newborn babies.
  • Avoid sudden switching on the lights in a dark room. If needed, turn on a dim yellow light. 

How to stop the startle reflex without swaddling?

While swaddling is a popular method to help soothe and prevent the startle reflex from waking a baby, some parents might seek alternatives for various reasons. Here are five ways to help minimize the startle reflex without swaddling:

  1. Offer a Pacifier: Sucking on a pacifier can provide comfort and a sense of security for many babies, which may help them self-soothe and potentially reduce waking from the startle reflex. The act of sucking can have a calming effect, helping to regulate their emotions and reactions to stimuli.
  2. Create a Conducive Sleep Environment: Make sure the sleeping environment is calming and conducive to sleep. This can include using white noise to provide a consistent auditory backdrop, which can mask sudden noises that might trigger the startle reflex. A slightly inclined sleeping position, ensuring it’s safe and recommended for your baby, might also help.
  3. Gentle Rocking or Holding: Gently rocking or holding your baby until they are in a deep sleep can help minimize the chance of the startle reflex waking them. The motion can be soothing and help simulate the movement they would have felt in the womb.
  4. Practice the ‘Drowsy but Awake’ Technique: By putting your baby down to sleep when they are drowsy but still awake, you can help them learn to self-soothe and fall asleep on their own. This skill can make them less likely to fully wake up if they experience the startle reflex during their sleep.

A crib that can identify the Moro reflex and act in time.

Parents who are great at dealing with Moro reflex suggest these tips and tricks. 

  1. Act as soon as your baby is startled by a loud noise.
  2. Soothe in ways that mimic the comfort of the womb immediately.
  3. Try and prevent any sudden change in balance.

Baby products today are not effective at dealing with things that can wake your baby up, like the Moro reflex. 

How could they be

None of them respond as soon as your baby wakes up or falls asleep. 

So we built a smart and responsive crib with a baby monitor that can identify the startle reflex and the Moro reflex. It also responds as soon as your baby wakes up and before they cry.

Are there other reflexes in newborn babies?

Yes, apart from the Moro reflex, newborn babies exhibit several reflexes that are automatic, involuntary responses to specific stimuli. Some of these reflexes are present from birth, while others develop within the first few months of life. Here are a few examples:

  1. Rooting reflex: When a baby’s cheek is stroked or touched, they will turn their head in the direction of the touch and open their mouth, searching for a nipple.
  2. Sucking reflex: If you touch a baby’s lips or put a finger or a nipple in their mouth, they will automatically start sucking.
  3. Grasp reflex: When you touch a baby’s palm with your finger or an object, they will instinctively grasp onto it. This reflex is quite strong in the first few months of life.
  4. Stepping reflex: If you hold a newborn upright with their feet touching a flat surface, they will make stepping movements, as if they are trying to walk. This reflex usually disappears after a few weeks.
  5. Tonic neck reflex: Also known as the fencing reflex, when a baby’s head is turned to one side, the arm on that side will straighten while the opposite arm bends at the elbow.
  6. Babinski reflex: If you stroke the sole of a baby’s foot, their toes will fan out and their big toe will move upward. This reflex disappears as the baby gets older.

These reflexes are a normal part of a baby’s development and usually disappear as the nervous system matures. They serve various functions, from helping with feeding to protecting the baby from potential dangers.


Q: What is Moro reflecx in babies?

A: The Moro reflex in babies is an involuntary startle response characterized by a sudden extension of the arms and legs, usually in response to a loud noise or a sudden movement.

Q: How long does the Moro reflex last?

A: The Moro reflex typically lasts until around 4-6 months of age, but it can vary from baby to baby.

Q: How to integrate moro reflex?

A: To integrate the Moro reflex, you can engage in gentle movements and activities that provide a sense of security and help the baby feel safe and supported.

Q: How to stop the Moro reflex without swaddle?

A: To stop the Moro reflex without swaddling, you can try creating a calm and soothing environment for the baby, using gentle touch and rhythmic movements and gradually introducing more self-soothing techniques as they grow.

Q: When does moro reflex end?

A: The Moro reflex tends to diminish and disappear between 4-6 months of age as the baby’s nervous system matures and they gain more control over their movements.


  1. Identifying Moro reflex. Cambridge University Press. 2000. “The Neurological Assessment of the Preterm and Full-term Newborn Infant.”
  2. Difference between Startle reflex and Moro reflex. ScienceDirect. 2008. “Startle Response.
  3. How long does the Moro reflex exist? PubMed. 1986. “The evolution of primitive reflexes in extremely premature infants.”

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