1970's Vintage MCM Pre-teen dress

This beautiful dress is such an iconic image of the 1970's and it is in perfect condition, as I didn't notice any flaws. The dress zips up in the back but is unbranded. 

The measurements, when laid flat, are the chest at 14-inches wide, the total length of the dress, measured from the back of the neck, is 27-1/2 inches long and the sleeves, measured from the shoulder, at 6-inches long, and they have a slight poof. The waist has an elastic band that is still stretchy and does have some give, but not much and it measures, (at rest) at 9-inches wide and 3-1/2 inches high.

The chest measurements for the dress, compared with current measurement, would put it as a child's 5-6, but its full length matches a womans extra small. With the waist being a wide elastic band, and if it was bunch up at the waist when worn, the total length of the dress could be 25-inches in length, which would put the dress, for length only, at a child's size 12-14. Please compare the measurements I have listed when you measure your child, as this dress is quite an anomaly. 

The dress comes from a smoke free home