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Moro reflex
Moro reflex
Neonate
Neonate

Moro reflex
Definition:
Moro reflex is a primitive reflex that is present at birth and typically disappears in the first few months of life. (See also infantile reflexes.)

Alternative Names:
Startle response; Startle reflex; Embrace reflex

Considerations:

The Moro reflex may be demonstrated by placing the infant face up on a soft, padded surface. The head is gently lifted with enough traction to just begin to remove the body weight from the pad (Note: the infant's body should not be lifted off the pad, only the weight removed).

The head is then released suddenly, allowed to fall backward momentarily, but quickly supported again (not allowed to bang on the padding). The infant may have a "startled" look, and the arms fling out sideways with the palms up and the thumbs flexed. As the reflex ends the infant draws the arms back to the body, elbows flexed, and then relaxes.
Common Causes:

This is a normal reflex present in newborn infants. Absence of the Moro reflex in an infant is abnormal. Presence of a Moro reflex in an older infant, child, or adult is also abnormal.

Two-sided absence of the Moro reflex suggests damage to the central nervous system (brain or spinal cord).

One-sided absence of the Moro reflex suggests the possibility of a fractured clavicle or injury to the brachial plexus, which can occur because of birth trauma. Conditions associated with brachial plexus injury include Erb's palsy and Erb-Duchenne paralysis. Paralysis on one side of the body may also produce an asymmetrical Moro reflex.
Home Care:
Be very careful if attempting to test the Moro reflex on your own: you do not want the baby to bang his or her head or fall.
Call your health care provider if:
  • you suspect your infant may have a fractured clavicle or a brachial plexus injury (causing loss of the Moro reflex on one side).
What to expect at your health care provider's office:

The medical history will be obtained and a physical examination performed.

Medical history questions may include:

  • history of the labor and birth
  • detailed family history
  • other symptoms

Note: An abnormal Moro reflex is usually discovered by the health care provider.

PHYSICAL EXAMINATION
The Moro reflex will be evaluated. The muscular system and nervous system may need to have detailed examination, if the reflex is absent or abnormal.

Diagnostic tests, in cases of decreased or absent reflex, may include:

AFTER SEEING YOUR HEALTH CARE PROVIDER
You may want to add a diagnosis related to an abnormal Moro reflex to your child's personal medical record.
Review Date: 5/20/2002
Reviewed By: Elizabeth Hait, M.D., Department of Pediatrics, Rainbow Babies and Children's Hospital, Case Western Reserve University, Cleveland, OH. Review provided by VeriMed Healthcare Network.
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