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Moro Reflex: Triggers, Clinical Significance & Ways to Calm Moro Reflex

What is Moro Reflex?

The Moro Reflex which is also termed as a startle reflex is defined as an involuntary motor response that is seen in newborns shortly after birth. Moro Reflex can be explained as the infant suddenly spreading their arms and moving their legs and then bringing the arms in front of the body. Moro reflex is the first thing that physicians check immediately after the birth of a child[1, 2, 3].

Other reflexes that physicians check in a baby after birth include rooting, sucking, stepping, and grasping. The Moro Reflex is quite evident when the baby is startled. This can be due to some sound or a noise. In some cases, the baby may even cry during Moro Reflex[1, 2, 3].

What is Moro Reflex?

Sometimes, a baby may have an abnormal Moro Reflex. In this, only one part of the body is involved and the rest of the body will show no signs of the Moro Reflex. This may be caused due to injuries during delivery, certain infections, peripheral nerve damage and spastic cerebral palsy[1, 2, 3].

What Are The Triggers Of Moro Reflex?

As stated, Moro Reflex is often triggered when the baby is startled. This can happen due to a sudden loud noise, bright lights, and sudden movements during sleep. If a baby has a sensation that it is falling then that also can trigger a Moro Reflex[3].

The baby gets this feeling when their parents or caregivers are just laying them down in the bed or when they pick them up. The best way to check for a Moro Reflex is by conducting a head drop test. This test is done by gently lowering the head of the baby to induce a sense of falling[3].

What Is The Clinical Significance Of Moro Reflex?

The clinical significance of Moro Reflex can be best understood by studying abnormal Moro Reflex. As stated, an abnormal Moro Reflex can be caused due to several factors. A baby can have severe asphyxia at the time of birth which can give rise to an abnormal Moro Reflex. Some babies also have intracranial hemorrhage which can be a cause of an abnormal Moro Reflex[1].

A baby with a prolonged Moro Reflex is a clear indication of spastic cerebral palsy. Some studies suggest that the presence of or absence of Moro Reflex is related to the growth and development of the baby in the womb and less commonly due to medical conditions[1].

However, there is another study which claims that there is a clear link between Moro Reflex and motor development in premature babies and babies who have very low weight at the time of birth[1].

What Can Be Done To Calm Moro Reflex?

A symmetric and normal Moro Reflex is an indicator that the baby is normal and healthy. However, there are cases where this reflex is exaggerated and overactive. In such cases, the reflex can be triggered even by minute sounds. This at times interferes with the sleep of the newborn. Rarely, an overactive Moro Reflex an also be a sign of hyperekplexia which is an inherited neurological condition. These babies have overactive startle response with periods of muscle rigidity and even followed by paralysis which is quite brief. There is also hypertonia observed in people with hyperekplexia. This makes it tough for the baby to move the extremities[3].

Aside from this, Moro Reflex is absolutely normal and should not be a cause of worry to the parents or caregivers. This reflex is the baby’s natural reaction to the outside world when they come out of the womb. A baby displaying Moro Reflex and seeming to be disturbed buy it can be calmed by moving the baby’s arms and legs gently towards the body[3].

The parents can also hold the baby close to them till the time they calm down. It is important that the baby’s head and neck should be held while picking the baby up or lying it down. Swaddling is also quite a preferred way to calm a baby in distress due to overactive Moro Reflex. Swaddling is a term used to wrap the baby in a lightweight cloth so that the hands and legs are close to the body so that they do not get startled when asleep[3].

While swaddling has been practiced since ages, the National Institutes of Health states that this increases the risk for sudden infant death syndrome in case the baby rolls on their stomach. They opine that the babies should be placed with their back up and face towards the floor when they sleep when the parents resort to swaddling[3].

In conclusion, Moro Reflex is a normal reaction of the baby to the outside world after it is born. In fact, Moro Reflex is the first thing that is tested by physicians immediately after the delivery of the child. Some parents get worried when they see the baby displaying Moro Reflex for the first time. However, this reflex is completely normal and is not a cause of worry[1, 2, 3].

The Moro Reflex usually goes away by the time the baby is four months of age and is able to lift his head up on its own. In some cases, only one part of the body is involved during Moro Reflex. This is called as an abnormal Moro Reflex and physicians look for a cause of it and treat the baby accordingly. This can happen due to a variety of causes, including infections, spastic cerebral palsy, and muscle weakness[1, 2, 3].

Some children also have an overactive Moro Reflex. This at times can interfere with the sleep of the baby. In such cases, the parents can contact their physician to identify the cause of it and to ensure whether any type of treatment is required or not[1, 2, 3].

A baby displaying Moro Reflex can be calmed down by holding the baby close to the body as this is quite comforting to them. Additionally, swaddling the child that is wrapping the child in a thin blanket to keep the arms and legs close to the body is also a good way to calm the baby down during Moro Reflex[1, 2, 3].


Pramod Kerkar, M.D., FFARCSI, DA
Pramod Kerkar, M.D., FFARCSI, DA
Written, Edited or Reviewed By: Pramod Kerkar, M.D., FFARCSI, DA Pain Assist Inc. This article does not provide medical advice. See disclaimer
Last Modified On:December 30, 2021

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