06/13/2026
The Moro reflex (also called the startle reflex) is something babies are born with and is the sign that their brains and nervous systems are still developing.
It’s an automatic newborn response where a baby:
* suddenly throws their arms out
* then pulls them back in
* often with a startle or cry
It’s triggered by things like:
* a loud noise
* a sudden movement
* a feeling of falling or head drop
This reflex is part of normal nervous system development and is thought to be an early survival mechanism, basically a way for the baby to react to sudden danger or loss of support.
It usually:
* appears at birth (even in preterm babies)
* starts to fade around 3–4 months
* is typically gone by about 4–6 months as the nervous system matures