MedlinePlus Medical Encyclopedia: Moro reflex

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Moro reflex

Contents of this page:
Illustrations Alternative names Definition Considerations	Common Causes Home Care Call your health care provider if What to expect at your health care provider's office

Illustrations

Moro reflex

Neonate

Alternative names Return to top

Startle response; Startle reflex; Embrace reflex

Definition Return to top

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.)

Considerations Return to top

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 Return to top

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 Return to top

It is NOT necessary to ehck for a Moro reflex at home. Your doctor will check at the baby's visit.

Call your health care provider if Return to top

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 Return to top

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:

clavicle or shoulder joint X-ray
tests for disorders associated with brachial plexus injury

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.

Update Date: 5/4/2004

Updated by: Katrina McPherson, M.D., Department of Pediatrics, Jackson Memorial Hospital, Miami, FL. Review provided by VeriMed Healthcare Network.

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