Prompt, please, from what age safely to use " kengurushk...

[The anonym]

Prompt, please, from what age safely to use "kengurushkoj"? It is necessary only for the house, t. e. On short time intervals. Thanks.

[Porohnja V.S.]

The child promptly grows in infancy. Any compelled or forced not physiological poses break development of a backbone. Really it so is necessary to you - cannot be kept in these or it " short intervals "?