The Moro Reflex: Understanding Why Your Baby Gets Startled

Why does baby startle? It’s called the moro reflex. Find out why babies have this, how to keep baby from startling himself awake, and when it goes away.

Moro Reflex Understanding Why Baby Gets Startled by Mama Natural

Have you ever heard a new parent joke that life would be easier if babies came with manuals? Well, of course, babies don’t come with how-to manuals, but they do come fully equipped with nine reflexes, like the moro reflex, unique only to newborns. While these reflexes don’t give us all the answers to parenthood, these reflexes do actually make life easier for both the babies and parents.

Think about it: the rooting and sucking reflexes sure do help facilitate the breastfeeding process! But what about the moro reflex. What’s the point of that one?

Fun fact: If you’re wondering what the word Moro means: Ernst Moro was the first person to describe and study this reflex.

What is the Moro reflex?

The Moro reflex, also referred to as the startle reflex, is one of several reflexes that newborn babies naturally exhibit; it’s one out of nine to be precise. The Moro reflex occurs when a baby is sleeping and is suddenly started awake.

What does the Moro reflex look like? The Moro reflex definition isn’t like the nice slow gradual wake ups we long for on lazy Sunday mornings; the Moro wake up is quick and abrupt. Most babies inhale sharply while their arms fly up over their heads. Baby pulls his knees up to his chest, and eventually he will lower his arms, cross them, and return to a fetal position.

When a baby experiences the Moro reflex, he won’t be able to settle back down on his own. The sensation of the Moro reflex is very jarring and can even scare a baby since he perceives the event as a free fall. Imagine you were sleeping and when you woke up, you falling out of a sky diving plane. Terrifying, right? Although that is an improbable situation, that is the sensation that baby feels – even if he’s not really falling. This reflex is designed to protect baby from danger; even preemie babies born at 25 weeks have demonstrated this reflex.

Once the startle reflex has been initiated, your baby will experience two phases:

Phase 1: The arms flail, baby inhales air, and he may begin to cry and / or fuss. This is the part where baby feels the falling sensation. Some researchers think that babies extend their arms outward to make themselves easier for a parent to catch.

Phase 2: During this phase, baby resumes the fetal position. The same study has a hypothesis for this phase as well. If the baby hasn’t been caught by a parent (or anyone) during the free fall, baby’s instincts take over and assume the fetal position – in order to best brace for impact of a fall. Pretty cool when you think of how a baby is wired to try to protect himself during falls.

If your baby isn’t really falling, you may wonder why he even startles awake. Even though it may cause you to hit the nighttime routine circuit again, the Moro reflex is a very good thing for a baby to have. In fact, it is a sign of healthy nervous system.

Moro reflex triggers

Let’s be honest: you probably videotaped your baby’s Moro reflex a time or two (who hasn’t?), but if it keeps happening during nap (or bed) time, you probably want to know what the triggers are and how to avoid them. Common triggers include:

  • Auditory: loud, sudden noises like a slamming cabinet or clanging pot or a neighbor banging on the front door
  • Visual: changes in light like opening the curtain in the nursery during naptime
  • Touch: a sudden touch or a quick movement like standing up after you’ve been sitting with a sleeping a baby
  • Shifting movement: anything that makes the baby feel unsupported like being lowered into a bassinet while sleeping

The good news is that some of these external triggers are easy to avoid. For example, some parents swear by white noise machines for their nurseries to help drown out the sudden noises of a busy household.

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Is the Moro reflex an issue for babies?

Is the Moro reflex an issue? Well, the answer to that question is yes and no. On one hand, a baby demonstrating the Moro reflex is demonstrating the health of his nervous system so there’s no issue in that sense.

Just to repeat: the presence of the Moro reflex is a good thing.

On the other hand, however, when a baby flails and wakes himself up, he is very likely to be upset and cry. Who wouldn’t be upset when a cozy nap is so suddenly interrupted?

While naptime disruptions are an inconvenience, the issue grows even bigger when mom and dad’s sleep is also interrupted. If the Moro reflex wakes up baby during the night, mom and dad also wake up. In this sense, reducing the Moro reflex incidences may help the whole family lose less sleep.

Ways to reduce the Moro reflex

If the Moro reflex is causing your little bundle of joy to miss out on some zzz’s, you may be anxious for ways to reduce the Moro reflex. No one – even a little baby- likes to be shortchanged on sleep.

  • Swaddling: Because studies show that swaddling has a “significant inhibitory effect” on the Moro reflex, swaddling your baby may be a good option for reducing Moro-induced wake ups. To avoid overheating, opt for a lightweight, natural fabric such a muslin swaddling blanket. If you’re new to swaddling and worried about positioning baby’s hips wrongly, opt for an organic Swaddleme – no wrapping involved. Regardless of what you swaddle your baby with, swaddling works because the baby feels safe and secure – a feeling much like being snuggled close to Mama in the womb.
  • Babywearing: One of the trickiest parts of laying a baby down for a nap is the actual laying-baby-down bit. Babywearing solves that problem because the baby is literally touching Mama (or Papa) so there is closeness, warmth, and love. It’s much more difficult to startle a baby when he is nestled that closely and tucked in so safely. Whether you perfect your wrap skills or opt for a structured carrier, this is a great choice for keeping baby calm.
  • Co-sleeping: Co-sleeping can be a beautiful arrangement, but a bouncy mattress or a parent that tosses and turns all night can stimulate the Moro reflex quicker than you can say Lights Out. If you co-sleep, avoid sudden moves and –if feasible – invest in a new non-noisy, non-bouncy (preferable natural) mattress.
  • Transferring baby: Have you ever sang multiple lullabies, swayed for hours (okay, it just seems like hours), and shushed and kissed your baby to sleep and then you went to lay him down and THEN HE SUDDENLY WAKES UP? It’s frustrating, but transferring your baby (to your bed, a crib, a bassinet, or a co-sleeper attachment) can be improved. Lay your baby down gently and slowly. Try not to move too fast or lighten your grip; you want to avoid that unsupported feeling. Once your baby is laid down, keep your hands on him for a moment or two. Then, release your hands slowly. The sudden removal of your hands can feel scary to a newborn.

When does the Moro reflex go away?

If the Moro reflex has kept you up at night – or woken you up – you have one question on your mind. When does the Moro reflex go away? Luckily, this sleepy time interruption is short-lived and typically fades away between 3-6 months of age. Around that time frame, baby begins to feel more secure, adjusts to this side of the womb, and gains more control of bodily movements.

What if my baby doesn’t have the Moro reflex?

As parents, it’s our job to worry about our kids, right? We might be tempted to worry that the Moro reflex wakes up our baby too much, but what if we start to worry about the lack of Moro reflex? Research links the lack of this reflex with potential issues with the brain and even birth-related injuries. Because the Moro reflex is such an important indicator of a healthy nervous systems, pediatricians check for this reflex at birth and then again at well baby visits.

Your doctor may test your baby’s reflex by recreating a falling feeling by lifting your baby’s body weight off of a hard surface. You can take a peak here:

Don’t hesitate to speak with your child’s pediatrician if there is an absent Moro reflex.

How about YOU ?

I would love to hear about your experiences, particularly…

  • What has been your experience with the Moro reflex?
  • Has swaddling helped your baby?
  • What other calming methods worked for you and your babe?
  • When did the Moro reflex stop for your baby?


Genevieve Howland

About the Author

Genevieve Howland is a doula and childbirth educator. She is the bestselling author of The Mama Natural Week-by-Week Guide to Pregnancy and Childbirth and creator of the Mama Natural Birth Course. A mother of three, graduate of the University of Colorado, and YouTuber with over 135,000,000 views, she helps mothers and moms-to-be lead healthier and more natural lives.


  1. Analyzing the fascinating world of baby surprise reflex unraveling the reasons behind your baby’s sweet surprises.
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  2. My baby girl is 5 months old now I have heard the worst experience with this and I have been really stressed until I found out it’s normal and am not the only one going through it holding her to sleep in my arms has been my sleeping method Its not yet over but am hoping by 6 months it will be gone

  3. One day while getting my diaper bag ready to go out, my daughter was on her swing and fell asleep she then suddenly woke up startled and and flailed her arms straight out and they got really stiff, at the same time it looked like she either was holding her breath or couldn’t catch her breath. Immediately I stopped the swing and held her she calmed down after that, but idk whether to be worried or not

  4. My NB is 3 weeks old and he likes to fall asleep laying on my chest and whenever I go to lay him down in his bassinet on his back he has multiple startle reflexes once I put him down and eventually starts to cry. So this momma is getting no rest. I recently found out that the only way he will sleep silently is on his stomach which I’ll do sometimes while I’m awake only. But at night getting him to sleep on his back so I can sleep is y very challenging. I feel undefeated

  5. My baby is 9 months old and is still easily startled by loud noise. Should I be concerned?

  6. My baby is 5 month and it has really effected him from going to sleep. He is too old to be swaddled is there anything else that can be done to ease him into a good sleep?

  7. My daughter is 9months old she was 2 1/2 months premature and she just staerted this reflex is that normal

  8. Interesting article! I’m in the unfortunate crossover where my four month old is rolling so we’re transitioning out of swaddling. But still constantly startles house myself awake!!! Fun times!

    • Inhibiting the Moro reflex through swaddling leads to sensory processing disorder. What you’re describing is a hyper-sensitive central nervous system that thinks normal sensations (like clothing textures, etc) are painful or uncomfortable. The Moro reflex has to fire in the newborn face to prevent this disorder from happening. Swaddling stops the reflex from firing. We treat this in our pediatric therapy clinic. Recommend you seek an occupational therapy evaluation for your little guy!

  9. It is important to know Why Moro Reflex Occurs & what to expect after Moro Reflex?

  10. My daughter is 4 months 10 days and she recently start showing these symptoms- is this normal for it to be shown now when it must be settled by now

  11. My son is 16 months old and he hasn’t lost this reflex yet. I have to stay right next to him until he falls into a deep sleep because he gets scared otherwise we he is startled. Do you know anything about this lasting into toddlerhood and if it means anything negative. I know it’s worse when he is overtired or stressed. He is also very sensitive to movement and to some textures or tight clothing. Thoughts?

    And thank you for everything you do! I’ve been following you for awhile and SO grateful for everything you’ve taught me!

    • Hi Hannah! Usually the Moro reflex only lasts 4-6 months, but sometimes babies and toddlers can just become startled in a way that is not reflexive. I would definitely reach out to your pediatrician or family doctor if you have any concerns! We love that you’re a long time follower!

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