Startle Reflex in Babies – Causes And Treatment

6 min read

Written by Aparna Hari

Aparna Hari

Her experience in impactful writing combined with her background in Home Sciences makes Aparna the perfect candidate for content writing in the pregnancy and parenting niche.

moro reflex in babies

Babies are a whiff of innocence that brings joy to the life of an adult couple. Observing a baby alone, indeed, brings refreshing yet new feelings to parents, although it’s sometimes not that easy. In fact, most parents experience a hard time balancing their domestic duties, work-life, romance, and parenthood. Yet, babies, too, have special needs. They require special care, especially during the initial stages when a newborn goes through reflex conditions. In this article, we talk about one such reflex called the startle reflex in babies.

In the course of your parenthood, understanding your baby’s concerns and taking care of the baby is crucial. Through the entire development process, you need to meet the particular needs of infants appropriately. Apart from diaper changing and feeding, parents need to understand the startle reflex that infants exhibit within their first few months of life.

In This Article

What is Startle(Moro) Reflex in Babies?

Startle(Moro) Reflex in Babies

Reflexes in newborn babies are an involuntary startle and almost automatic response to a particular stimulus. It’s also known as Moro Reflex. While sleeping, your infant does this reflexively in reaction to being dazed. It’s something just common that newborns often do. Yet, after a couple of months, they stop reacting like this.

However, in newborn babies, reflexes are an indication of developmental progress. You may notice several reflexes at certain stages of their growth. For instance, the rooting reflex, sucking reflex, gripping reflex, startle/Moro reflex, toe curl, and stepping. These are all expected at the initial stage of development and go away after a certain period of time.

If your baby often gets startled by a sudden movement, a loud noise, or shakes by the feel of falling — they might react distinctly. Arching their back, extending their legs and arms, or curling themselves up are the signs of the startle reflex. They might cry during this condition or not, depending upon their individual response to the startle reflex.

What Triggers Baby Startle Reflexes?

Triggers For Baby Startle Reflexes

Intense light, loud noises, and sudden movements usually trigger the startle or Moro reflex within a baby. Also, when a newborn suddenly moves, they can experience a startle reflex stimulus. Also, the sensation of falling can trigger this reflex condition. An infant might feel like falling down while parents pick them up or lay them down.

Your doctor may go through a thorough post-delivery check-up to diagnose this response. The doctor may do a head drop test to simulate the sensation in a baby by gently lowering the baby’s head close to the body.

When Does Startle Reflex in Babies Start?

The startle reflex remains present in a baby’s body at birth. During the first 12 weeks after birth, the newborn may exhibit the signs of startle reflex involving the legs, arms, and head parts of the body.

After 4 months, when the neck supports the head weight, the baby seems to have less intense or slight startle reflexes. The symptoms may only spread to extend or curl arms without moving legs or head. And after 6 months of the baby, the reflex symptoms disappear totally.

How Long Does Startle Reflex Last in Babies?

The dramatic Moro or Startle reflex starts showing up in the first few weeks after a baby is born. It triggers when a baby falls backwards or shifts the head abruptly, flares its legs and arms, or rapidly curls its arms together. However, the reaction may vary to various degrees in individual babies. Usually, the symptom peaks during the first few weeks; it stays up to two months and vanishes afterwards.

[Read : Basics Of Holding A Newborn]

How to Reduce Startle Reflex in Infants?

Reduce Startle Reflex in Infants

Startle reflex with normal reactions is healthy in babies and does not cause strict concern. It is common in babies as it makes newborns strong and helps them adjust to the world outside the womb.

However, you can comfort your infant who seems distressed or cries a lot due to starlet reflex.

  • Keep the baby near to your skin, so the baby feels the warmth of your body and settles down.
  • Swaddle the infant in a relaxing cloth or comforter. This technique will make the baby feel warm, safe, and secure. The coziness also helps your baby sleep a lengthy period.
  • Support the infant’s neck and head area while holding or moving them.
  • Shift their legs and arms gently toward their body.
  • The swaddle method helps the newborns keep their limbs close to the body and prevents them from startling while sleeping. So, let us talk about the swaddle strategy in detail.

The Swaddle Technique

Following are the easy steps of the swaddle technique:

  • Take a thin cozy blanket and lay it on a plain surface. Now point one corner up like a diamond shape.
  • Barely tuck one corner.
  • Now gently lay the infant on the blanket face-up, pointing the baby’s head at the border of the tucked corner.
  • Take one corner of the blanket and tuck it across the infant’s body snugly under them.
  • Now fold the bottom and up the portion of the blanket. And, of course, leave space for the baby’s leg and feet to move.
  • Take the last corner section of the blanket and pleat it underneath the baby’s body. It will leave the baby’s head plus neck part exposed.

[Read : All About Swaddling A Baby]

Treatment Options For Startle Reflex in Babies

With most babies, you do not need medical attention for startle reflex. This reaction is vital for the growth of a newborn, and there is nothing to get worried about.

The signs of startle reflex subside over time; however, you still can consider some precautions for your baby to prevent reflexes from waking them up. You can adopt some strategies, including:

  • Cropping loud noises.
  • Dimming the lights.
  • Avoiding sudden movements while feeding them.
  • Using a noise-preventing machine like a white noise machine while the infants are sleeping.
  • Purposefully shifting the baby’s position frequently.

When to Consult a Doctor?

When to Consult a Doctor

Though startle reflex is a positive sign in infants, many newborns might have an exaggerated or overstimulated startle reflex. It can often impede the sleep of a baby.

In fact, in rare cases, newborn babies may experience severe startle reflex – it can be an alerting sign of an inherited neurological condition named hyperekplexia.

Infants with hyperekplexia can show startle reactions following muscle rigidity and paralysis for a short period. They can also undergo hypertonia, an increased muscle tone condition that stiffens the limbs, making movement difficult for babies.

You must consult a doctor if you notice mild or severe startle reactions affecting one side of the baby’s body. It can be a potential sign of brain injury, spinal cord damage, or shoulder injury. Though medical concerns are typically not required for startle reflex, if it stays after 6 months, then visit a doctor immediately.

After birth, the involuntary reactions are typical and nothing to be scared of. First-time parents might get worried; however, it is a healthy reaction in infant babies. The signs diminish over time, possibly after 4 months. And if not, consulting a doctor becomes crucial.


1. Are Babies Supposed to Startle While Sleeping?

The startle or Moro stimulus is natural and expected in newborn babies. It’s a positive sign of a healthy nervous system and vital for a baby’s development.

2. What is the Difference Between Moro and Startle Reflex?

Moro reflex is often known as the Startle reflex, which occurs when a newborn gets startled by a sudden movement, loud sound, or intense light.

3. What Does the Startle Reflex Indicate?

Startle reflex is a natural process in infants when they startle from a sense of falling or sudden movements. However, the absence of startle reflex in newborns is abnormal and possibly indicates severe injury or disease.

Read Also: Let Down Reflex And Breastfeeding

Aparna Hari,MBA in Marketing,P.G. Diploma in Human Resource Management from IGNOU Bachelor of Sciences (Home Science) from Nagarjuna University

Her experience in impactful writing combined with her background in Home Sciences makes Aparna the perfect candidate for content writing in the pregnancy and parenting niche.Read more.

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