The Women's Journal explained it thus: "That pink being a more decided and stronger colour, is more suitable for the boy, while blue, which is more delicate and dainty, is prettier for the girl."
DressMaker magazine agreed. "The preferred colour to dress young boys in is pink. Blue is reserved for girls as it is considered paler, and the more dainty of the two colours, and pink is thought to be stronger (akin to red)." Taken from the article.
Interesting how fashion changes. Any thoughts?