Clothing for children must be loose to support full respiration and avoid compressing organs or restricting movement.

Original passage

Tight bands or waists hinder the action of the heart and lungs, and should be avoided. No part of the body should at any time be made uncomfortable by clothing that compresses any organ or restricts its freedom of movement. The clothing of all children should be loose enough to admit of the freest and fullest respiration, and so arranged that the shoulders will support its weight.