Muscle hypotonia in babies is not life-threatening, but it can affect their development in some cases. While most children outgrow this condition, there are also cases that are incurable.

Last update: September 14, 2021

Muscle hypotonia in babies is not a disease, but a clinical sign. In general, it is associated with some underlying pathology. It is characterized by sagging, lack of resistance to movements and lack of mobility in the baby.

Although there is no exact data in this regard, muscle hypotonia in infants is estimated to occur in 2 to 3% of newborns and infants. About 80% of cases are benign and progress positively.

Whatever the case, muscle hypotonia in babies it is a condition that must be detected and diagnosed promptly. The faster it is detected, the greater the chances of successfully treating and overcoming it.

Signs and Symptoms of Muscle Hypotonia in Babies

Babies with muscular hypotonia often have difficulty holding their head.

Muscle hypotonia in babies refers to a lack of muscle tone in newborns or infants. Healthy muscles are never completely relaxed, but always retain some degree of tension and rigidity. This is known as “muscle tone.”

That muscle tone is required to maintain a posture, for example, a straight back. If there is muscle hypotonia, this cannot be done normally. In the case of babies, there are some signs that can warn of the presence of this condition:

  • Difficulty holding the head.
  • “Soft” arms and legs. They look more stretched, flexible and arched than normal. When moved they do not present resistance.
  • Slow reaction. They take a little longer than usual to withdraw a limb when faced with a painful stimulus.
  • Difficulty latching on to the mother’s breast.
  • Suction difficulties.
  • Trouble turning on the belly, when they are upside down.
  • Decreased alert.
  • Weak crying and muffled voice.
  • Delay in crawling, walking, and motor activities.

In muscular hypotonia in babies the little one feels like “a rag doll”. It is flabby and appears as if it slipped from your arms when carried. It may take longer to talk and feed on his own.

What is the cause?

Muscle hypotonia in babies has multiple causes. It is almost always present from the first month of life, but it is not easy to detect it at that stage. It is also possible that it will appear later.



Sometimes muscle hypotonia in babies is a symptom of a disease of the central or peripheral nervous system. It is also possible that it is the result of problems during pregnancy or delivery. In a small percentage it is the effect of a hereditary problem.

Prenatal and natal causes

Muscle hypotonia in babies it may be the effect of pathologies present in the mother during pregnancy. Diseases such as diabetes mellitus, gestational diabetes, lupus, epilepsy, myasthenia, myotonia or joint hypermobility, among others, can cause the anomaly.

The same goes for maternal infections like herpes, rubella, etc. When mothers have had repeat abortions or have old age. there is greater risk of muscle hypotonia in babies. The same happens when the mother has ingested magnesium sulfate for high blood pressure or benzodiazepines.

Other factors that can generate this condition are infection at the time of delivery, trauma during delivery, hypoxia in the baby, lack of ventilatory support at birth, metabolic alterations in the newborn and others.

Underlying diseases

Some pathologies of the central nervous system can cause muscular hypotonia in babies. Within them. there are brain or spinal cord injury, cerebral palsy, and infections in the brain.

There are also peripheral nervous system conditions that lead to hypotoniasuch as muscular dystrophy, myasthenia gravis, spinal muscular atrophy, and Charcot-Marie-Tooth disease.

Secondly, there are non-neurological problems that cause muscle hypotonia in babies, as the following:

  • Down’s Syndrome.
  • Prader-Willi syndrome.
  • Tay-Sachs disease.
  • Congenital hypothyroidism.
  • Marfan syndrome.
  • Ehlers-Danlos syndrome.
  • Connective tissue disorders.
  • Being born before the 37th week of pregnancy.


Diagnosis and treatment

The doctor will evaluate the baby for the presence of muscle hypology and determine its causes.

Diagnosing muscle hypotonia in infants can take some time, as it is sometimes confused with conditions such as psychomotor retardation or encephalopathy. The usual thing is that an interview is done at the beginning to inquire about the family’s medical and genetic history, and the conditions of pregnancy and delivery.

Then the baby is given a physical exam. to assess your motor and sensory skills, reflexes, balance, coordination, and mental state. After that, the usual thing is that tests such as the following are ordered:

  • MRI or CT scan of the brain.
  • Blood test.
  • Electromyography (EMG). Measures nerve and muscle function.
  • Electroencephalogram (EEG).
  • Spinal puncture.
  • Muscle biopsy.
  • Genetic testing.

The diagnosis makes it possible to establish the cause of muscle hypotonia in infants. Treatment will depend on the origin of this condition. If the condition is inherited, there is no cure for it.

In general terms, the treatment focuses on stimulating, strengthening and working the muscles that provide stability and they act against gravity. These offer support for the baby’s movement so that later development is not affected.

Recovery and projection

The success of treatment for muscular hypotonia in babies depends largely on the daily work that parents do around the house. Such work includes massages and exercises indicated by a professional. In general, the following measures apply:

  • A sensory stimulation program. Encourages the appropriate response to stimuli.
  • Occupational therapy. To develop fine motor skills.
  • Physiotherapy. Helps to better control movements.
  • Speech and language therapy. Work on breathing, swallowing and speaking problems.

There are babies who do not need any treatment or a minimum, but it is the doctor who must indicate it. Recovery and future outlook depend on several factors such as: the cause, severity, age, and the affected muscles.

It is important to understand that muscle hypotonia in babies by itself is not life-threatening. Consistency in treatment is essential for improvement to be achieved. In lifelong cases, the child will need medical and emotional support.

Periodic check-up of the baby is essential

The importance of early diagnosis needs to be emphasized of muscular hypotonia in babies. Parents should be attentive to these signs of flaccidity and weakness in the child’s muscles, and consult with the doctor if they suspect them.

As we have seen, muscle hypotonia in babies can have multiple causes. The faster the origin is known and treated, the greater the child’s chances of successfully overcoming this condition.

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