High muscle tone in infants may cause the following hazards:

1. Retarded motor development: High muscle tone in infants will affect their muscle development and movement ability, leading to delayed motor development.

2. Postural abnormalities: High muscle tone in babies can lead to abnormal postures, such as head tilting back, arms bending, etc.

3. Nervous system problems: High muscle tone in infants may be a symptom of neurological problems, such as cerebral palsy.

4. Psychological problems: High muscle tone in babies may affect their mental health, such as anxiety, depression, etc.

5. Other health problems: High muscle tone in babies may also lead to other health problems, such as difficulty breathing, difficulty swallowing, etc.