the moro reflex

Mom’s Question:

My 4-month-old baby will be laying on the bed and suddenly throw out his arms like something has frightened him or he’s fallen and start screaming hysterically?? I’m not sure why? Is something wrong with him?

Tricia (IL)

Baby Help Line:

The Startle Reflex In Newborn Babies

What beautiful children, and such a lovely photo.

There is absolutely nothing wrong with your son. What you are seeing is a normal reflex present in all newborn babies. This startle reflex is called the Moro reflex. Because they have not yet got voluntary control over their little bodies, they can startle themselves by a jerk or sudden movement or a loud noise.

Some babies have the reflex movement but don’t seem to be concerned, others think the world is ending!

Babies startle with a sudden noise, or unexpected movement or sometimes even being touched when asleep. As they get more control over their bodies, around 5 – 6 months of age, the reflex disappears. Babies are usually tested for the Moro reflex after birth, as it is a really good indication of normal motor development.

This fear reflex is the only unlearned fear, all others we learn as we develop and experience the world. The reflex will make the baby tighten the body, fling his or her arms up and out and open up his or her usually tightly clenched fists. He or she will draw up the knees, and then bring the arms and re-clenched fists close to his or her body — almost as hugging himself.

You can see a short video clip of the Moro reflex in a newborn baby here below.

Your little boy should grow out of it in the next couple of months, so I wouldn’t be concerned, just comfort him when it happens.

Enjoy your lovely family,
Annie Desantis

Find answers and comments below.


Jun 27, 2014 4 month old does the same
by: Anonymous
My daughter is 4 months old and does the same thing. I have asked the doctor and they tell me not to worry, but as a mom, you can’t help but worry. She only does it when laying on her back or sometimes when you are changing her diaper. As soon as you pick her up she is fine. I just think it’s weird. How did your baby do? Did he grow out of it?

Jul 11, 2014 swaddle your baby
by: Anonymous
It might be an idea to swaddle your baby so that when she tries to move she meets resistance. This way she still thinks she’s in the safety of the womb and stays calm. You will probably find that she will sleep much better. Just make sure that you don’t wrap her legs up. When you swaddle her just concentrate on keeping her arms by her sides.
I swaddled my own daughter for the first three months she didn’t seem keen at first but she remained calm when she had a sudden movement and slept really well.

Jan 31, 2015 glad it’s not just my baby
by: jenbutterfly
My 4-month-old boy does it too since he was around 6 weeks. it started when I would put hiking on change table to change his nappie . then occasionally when I put him down on the bed. he looks so scared when it happens . it’s like he thinks his falling . :-(

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This Post Has 3 Comments

  1. S Burke

    Please know that another thing to consider is something called Infantile Spasms, a potentially catastrophic form of infant epilepsy. The seizures often present in a movement that looks an awful lot like the moro startle reflex and are often confused for this by doctors. Here is a video for reference.
    If you suspect your child is having this type of seizure please go to your doctor right away.

  2. Katherine Jameson

    When my LO started developing his startle reflex, he would cry
    multiple times throughout the night. I didn’t know what to do because
    this had been going on for a while and so I asked one of my friends. She
    suggested getting the Zipadee-Zip which is this sleeping suit from
    Sleeping Baby. I was reluctant at first, but to my surprise it actually
    worked. It covered my little guy like a swaddle, he felt soothed and
    comforted by the soft-fleece material, and the suit provided just enough
    resistance to calm him down whenever his reflex started up.