More about the Moro reflex: your baby's 'startle' response

The Moro reflex (so called because it was first described by physician Ernst Moro in 1918)

is one of our primitive reflexes – these are responses to stimuli that we develop before we are born. The reflexes are controlled by the primitive part of our brain and, as your baby develops and more connections are made in their brain, these reflexes become integrated, and you will see their judgement of danger manifest itself in different reactions.^[1]   

Your baby's Moro reflex is a 'startle' response, which can be stimulated by any of their sensory systems, but is often the response they show if they feel like they are falling or if there is a loud noise or bright light. Your baby will open their arms and legs and take a breath, they will then bring their arms and legs back towards their body and might cry. You might well have seen a health professional checking this reflex on your baby not long after they were born.^[2] 

A grip and breathing reflex inherited from our ancestors

The Moro reflex is thought to be one that we have retained from our ancestors to help us protect ourselves as babies from danger. This ancestral response would help a baby being carried or holding onto its mother to grab on if they started to fall.

The Moro reflex can also assist with a baby’s first breath after birth, as it not only triggers movement that might help a baby to get a better grip, it also activates the part of the brain concerned with breathing and causes the baby to take a breath. Babies usually take a breath in response to their chest being compressed and then this compression is released as they are born, but the Moro reflex provides another way to stimulate breathing if this compression and release of the chest is not sufficient.^[1]   

Will my baby always make this movement?

As your baby develops control of their movements and their ability to make judgements about danger, the Moro reflex becomes integrated. So, as time goes on, rather than seeing the Moro reflex, you'll notice that your baby startles by raising their shoulders and looking around. They will then either ignore or pay more attention to whatever startled them, so if they hear a loud noise and look and see that nothing is different to what they expect they will turn away again.

This is a gradual process at it requires your baby to make judgements about danger, as well as needing a more developed central nervous system, so that movements and responses are controlled by higher areas of the brain – the midbrain and cerebellum – rather than by the primitive brain, the brain stem.^[1] 

References:

[1]. Goddard-Blythe, S. (2004). The Well Balanced Child: Movement and Early Learning. Stroud: Hawthorn Press. 

[2]  Addyman, C (2020) The laughing baby: The extraordinary science behind what makes babies happy. London:Unbound.