What is moro reflex?
Babies are born with several reflexes intended to help them survive during their first few months. One of the most important is the Moro reflex, also known as the startle reflex. This involuntary response is normal in infants, and doctors will check to make sure it is there after delivery and in follow-up visits.
In most cases, the Moro reflex begins to disappear about three months after birth. After six months, the reaction should be completely gone for most infants.
Signs of the moro reflex in babies
The Moro reflex is a simple physical reaction, so it's easy to identify.
1. Extended arms and legs
2. Arms and legs drawn In
The baby will pull all their limbs closer to their body. This may look like an embrace or an adaptation of the fetal position.
Causes of the moro reflex
The Moro reflex is natural and should be expected in newborns. It is the sign of a healthy nervous system. The response is triggered by a startling event, such as changes in noise, light, or sudden movement.
While parents can take steps to avoid needlessly prompting the reflex, it’s impossible to avoid it altogether. Still, it helps to understand the most common triggers, which include the following:
Babies, like adults, are easily startled by loud and unexpected noises. Volume is not always the determining factor in whether the Moro reflex occurs, however. If noises are both loud and sudden, they are more likely to spark a significant reaction.
Sudden changes in light intensity can trigger the Moro reflex. Examples could include turning on bright lights or opening the window in a previously dark room.
Sudden movements during breastfeeding or other interactions may spark the Moro reflex. Babies can also trigger the reaction themselves as they move their arms or legs.
Changes in altitude
The Moro reflex often occurs as babies are moved from one position to the next. For example, many parents inadvertently trigger the reflex when setting down babies to nap in cribs or bassinets. The change in altitude sparks a falling sensation, which, in turn, prompts the reflex and may wake the baby.
When to see the doctor about the moro reflex
While the Moro reflex is important in the first few months of life, it gradually subsides as infants grow.
Medical attention is typically not needed for a strong Moro reflex, which ordinarily diminishes with time. If, however, the reflex still seems strong after six months, a visit with a physician may be worth considering.
Diagnosing the moro reflex
When checking for the Moro reflex, most physicians use a test known as the head drop. During this test, the doctor mimics the sensation of falling by raising, and then slowly lowering, the baby’s head below the level of the body.
Treatments for moro reflex
With most babies, the Moro reflex does not need to be addressed. This reflex is crucial for newborns and is nothing to be concerned about. If the reflex does not begin to subside over time, however, you can take measures to prevent babies with especially strong reflexes from waking themselves.
Swaddling is one of the most popular and effective solutions for addressing concerns associated with the Moro reflex. This practice limits the reflex's impact on sleeping infants, who may wake themselves with sudden limb movements. To use this technique effectively, swaddle infants tightly and keep their arms contained.
Because another common trigger is change in movement, using slow movements, such as when putting a baby in their crib, can reduce the likelihood of triggering the response.
The Moro reflex can also be limited by controlling infants’ environments. Key strategies for doing so include:
- Dimming the lights
- Limiting loud noises
- Using a white noise machine while babies are sleeping
- Avoiding sudden movements while nursing or feeding with bottles
- Moving slowly and purposefully when changing a baby's position or location
Parenting and Newborn Resources
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International Board of Credentialing and Continuing Education Standards: “What to know about the Moro reflex.”
International Journal of Pediatrics: “The Grasp Reflex and Moro Reflex in Infants: Hierarchy of Primitive Reflex Responses.”
MedlinePlus: “Moro Reflex.”
StatPearls: “Moro Reflex.”
Rhythmic Movement Training International: “The Reflexes - Moro Reflex.”
Stanford Children’s Health: “Newborn Reflexes.”