A Christening gown or christening robe is a very long, white infants' garment now mae especially for the ceremony of christening and usually only worn then. They are in fact the normal, or at least "best", outer clothing of Western babies until about the 19th century. The moment of progression to shorter dresses (for both boys and girls) was known as "shortcoating", which presumably coincided with the beginning of walking, which was impossible in a long robe.