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Moro's reflex is an involuntary movement of the baby's body, which is present in the first 3 months of life, and in which the arm muscles react protectively whenever a situation that causes insecurity happens, such as loss of balance or when there is a sudden stimulus, for example, when the baby is rocked abruptly.
Thus, this reflex is similar to the reflex that children and adults have when they feel that they are falling, and indicates that the baby's nervous system is developing correctly.
This reflex is usually tested by the doctor shortly after birth and can be repeated several times during the first pediatric visits to ensure that the nervous system is intact and developing properly. Thus, if the reflex is not present or if it continues throughout the second semester, it may mean that the baby has a developmental problem and the cause should be investigated.
How the reflex test is done
The simplest way to test Moro's reflex is to hold the baby with both hands, placing one hand on the back and the other supporting the neck and head. Then, you should stop pushing with your arms and let the baby fall 1 to 2 cm, without ever removing your hands from under the body, just to create a little fright.
When this happens, the expectation is that the baby will first stretch his arms and then immediately fold his arms towards the body, relaxing when he realizes he is safe.
How long should Moro's reflex last?
Normally, Moro's reflex is present until around 3 months of life, but its disappearance may take longer in some babies, since each one has a different development time. But as it is a primitive reflex of the baby, it should not persist in the second half of life.
If the reflex remains for a long time beyond 5 months, it is important to consult the pediatrician to make a new neurological evaluation.
What does the lack of reflection mean
The absence of the Moro reflex in the baby is usually related to the presence of:
- Injury to the nerves of the brachial plexus;
- Fracture of the clavicle or a shoulder bone that may be pressing on the brachial plexus;
- Intracranial hemorrhage;
- Infection of the nervous system;
- Cerebral or spinal cord malformation.
In most cases, when the reflex is absent on both sides of the body it means that the baby may have a more serious problem, such as brain damage, if it is absent in just one arm, it is more likely to be related to changes in the brachial plexus.
Thus, when the Moro reflex is absent, the pediatrician makes a referral to a neuropediatrician, who may order other tests, such as a shoulder X-ray or CT scan, to try to identify the cause and, thus, start the most appropriate treatment.