You have done it all, your baby has been fed, has a clean diaper, and you are finally able to put her down for a peaceful rest when all of a sudden, something startles her (even though you were as careful and gentle as possible and the room is extra quiet). You watch her arms and legs extend out quickly, she may gasp or let out a little whimper or cry and then just as quickly as her body jerked, she pulls her arms and legs back in to the original position. Sometimes she may need to be soothed and other times she goes right back to sleep. She doesn’t seem very bothered by that sudden startle but you’re thinking, what the heck just happened?! Did she have a nightmare, did something scare her, is she okay??
Stay calm because she is okay and everything that just happened in those few seconds is developmentally appropriate. What you just witnessed is the Moro Reflex, also known as the startle reflex. In fact, your pediatrician will likely check that your baby has this reflex at their well-visit by mimicking the sensation of falling by raising and then slowly lowering baby’s head below the level of the body. The startle response usually happens when she’s exposed to a loud noise or feels like she’s falling (hence the doctor lowering your baby’s head, imitating that falling motion). It’s actually a survival instinct to help baby know to cling to her mother if she is in fact falling. The startle reflex is really only prevalent in baby’s first two months of life.
When do you see the startle?
You’ve been rocking your baby to sleep for what seems like hours and he finally calmed down and drifted off. You reach over the crib to place him down nice and gently, and all of a sudden he startles and wakes. Thank you, Moro Reflex! Or you might be on a nice walk in the neighborhood with your sleeping babe in the stroller when you hit a bump on the sidewalk, hello Moro Reflex!
What should you do to prevent it?
There’s no need to prevent this reflex from happening during wake windows as it’s all part of typical development. But lots of free movement time and opportunities to stretch out are very important to help integrate primitive reflexes, meaning they will disappear naturally. While the Moro Reflex is completely normal, it can cause babies to wake themselves up during longer sleep sessions. Try swaddling at night to prevent that falling sensation and help baby (and you) get much needed rest.
The Moro Reflex may look startling (hahaha so PUNny), but its actually a good thing. It means your new baby has this primitive reflex that babies should be born with. With plenty of floor time to stretch out, baby’s movements will start to become less reflexive and more controlled. The startle response from the falling sensation or loud noises should disappear at around 2 months. If you continue to notice the Moro Reflex at 4 months, or you notice the reflex looks asymmetrical between the right and left sides of the body, please reach out to your pediatrician.
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