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Article: When Does The Startle Reflex Go Away?

When Does The Startle Reflex Go Away?

When Does The Startle Reflex Go Away?

New parents often wonder when their baby's startle reflex will go away. This reflex, also known as the Moro reflex, is a natural response in babies that

Babies will fly their arms and legs when they are startled or encounter sudden movements. Understanding the startle reflex is crucial for parents in parenthood. So, when exactly does the startle reflex end? Let's explore this part of infant development together.

What is startle reflex?

The startle reflex, also known as the Moro reflex, is a natural response in infants. When infants are confronted with sudden movements or startled by loud noises, they will outstretch their arms and legs and then quickly retract them. This reflex is thought to be an instinctive respond that helps babies protect themselves from potential danger. This reflex is usually seen in newborns and diminishes with age, eventually disappear.

What triggers the startle reflex?

A variety of stimuli can trigger the startle reflex or Moro reflex. Here are some common triggers:

Sudden loud noises:

Babies have highly sensitive ears and can be easily startled by sudden loud noises, including a slamming door or loud thunder. When babies hear sudden sounds, they may have startle reflex, causing them to move their arms and legs.

Sudden movements:

Infants have a keen sense of movements. Sudden movements always can catch them off guard. A sudden bump in the crib or being picked up quickly both can trigger the startle reflex. Babies' instinctive response is to stretch their limbs outward.

Light changes:

Light plays an important role in an infant's sleeping environment. Sudden changes in light can startle babies. If a bright light is suddenly turned on in a dark room, or if babies are exposed to a sudden flash of light, it can trigger their startle reflex.

Sudden temperature changes:

Infants are very sensitive to temperature changes. Whether babies are moving from a warm environment to a cool environment or from a cool environment to a warm environment, these sudden changes trigger the startle reflex.

Sudden falls or drops:

Babies are usually held in the arms of parents or safely in their cribs, but accidental falls or drops can occur. Even a slight fall or unexpected movement can startle them, triggering the startle reflex.

Understanding these triggers can help parents anticipate their baby's startle reflex and find some ways to comfort their babies in time.

How long does startle reflex last?

Parents are often confused about how long do their baby's startle reflex last, and want to understand different stages of it.

Birth - the First Few Weeks

Initially, the startle reflex appears after a baby is born, usually within the first few weeks. At this early stage, the reflex is very pronounced, and infants may show exaggerated responses to sudden stimuli, such as extending their arms and legs at a loud noise or sudden movement.

2-3 Months

Over time, the strength of the startle reflex diminishes, which signaling that the infant has entered the middle stage of startle reflex. At this stage, when the infant is two to three months old, the reflex becomes less pronounced compared to the first stage. While the startle reflex is still present, it is no longer as intense or frequent as it once was.

4-6 Months

Finally, infants typically enter the final stage of the startle reflex at four to six months of age. During this time, the reflex becomes less pronounced and eventually disappears completely. Infants will still respond to sudden stimuli, but their responses tend to be less pronounced.


The above information of for your references, each infant is unique and the timeline for the disappearance of the startle reflex may vary slightly from infant to infant. Understanding these stages may help parents guide their baby's development.

When does the startle reflex go away?

Parents often ask when their baby's startle reflex goes away. Generally, the startle reflex begins to diminish when infants are three to six months old. At this time, infants have more control over their movements and the startle reflex becomes less pronounced. The startle reflex generally disappears completely around six months to one year of age, although some infants may still show a reaction to sudden stimuli beyond this age.

Note: Every baby is different and the time at which the startle reflex disappears may vary.

How to stop startle reflex?

Here are some suggestions on how to soothe or minimize your baby's startle reflex:


Swaddling involves wrapping your baby tightly in a blanket or use a swaddling sleep sack to simulate the cozy environment of the womb. Swaddling helps to limit your baby's limb movements and reduces the intensity of the startle reflex. When swaddling, it is important to make sure that the blanket is wrapped securely but not tightly to allow some movement of the hips and legs to prevent hip dysplasia.

What is the hip dysplasia?: Hip dysplasia is a condition in which the hip joint is not properly shaped. In infants, hip dysplasia may develop before birth or in the first few months of life. Regular checkups with your pediatrician can help detect hip dysplasia early and ensure that your baby has the proper treatment.

How to stop startle reflex without swaddling?

Gentle touch and soothing sounds:

Gentle touch and soothing sounds can comfort your baby and help ease their startle reflex. Gently stroking your baby's back or gently rocking their body can help calm their nervous system and reduce the possibility of them being startled by sudden stimuli. Playing calming background music or white noise can also create a soothing environment and minimize the chance of triggering the startle reflex.

Gradual transitions during sleep:

Babies are particularly sensitive during the transition between wakefulness and sleep. You can try establishing a calming bedtime routine to signal to your baby that "it's time to go to sleep." You can do some activities such as dimming the lights, reading a bedtime story or giving them a warm bath. Gradually putting your baby to sleep can help reduce the sudden awakenings.

Provide a safe and comfortable sleep environment:

Creating a safe and comfortable sleep environment is essential to reducing the startle reflex during sleep. Make sure your baby's crib or bassinet is free of any potential hazards, and sleep your baby on his or her back as recommended by the pediatrician. Using a firm mattress and avoiding loose bedding or soft toys will also help create a safe sleep environment and reduce the risk of sudden movements that may trigger the startle reflex.

Encourage tummy time:

Tummy time is critical to your baby's development and can also help reduce the intensity of the startle reflex. By encouraging your baby to sleep on his or her tummy while being companied by their parents. Tummy time can help your baby strengthen his or her neck, shoulder and arm muscles so that they are more coordinated and less likely to be startled by sudden movements. As your baby grows, gradually increasing the time spent on their tummy can improve their motor skills and their ability to resist the startle reflex.

By using these strategies into your daily routine, you can help minimize your baby's startle reflex and create a calm, soothing environment for them.


In conclusion, knowing when the startle reflex goes away can reassure parents about their infant's developmental process. By mastering some gentle calming techniques and creating a safe sleep environment, parents can help minimize the impact of the startle reflex on their baby's sleep.

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Yujia Shi

An expert in sleep sack design, is a valued contributor to Kaiya Baby's blog. With a strong background in baby sleep bags and maternal care, she is highly regarded for her professionalism. Yujia Shi prioritizes baby comfort and safety in her designs, using high-quality materials. Her insightful articles on sleep bags have been featured in reputable publications and have gained a significant readership. Trust Yujia Shi to help you create a comfortable and safe sleep environment for your baby, backed by her proven track record in the industry.

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