Pink is for ... boys?
It seems that the pink is for girls, blue is for boys color/gender association is a relatively recent Western phenomenon.
Prior to the early 20th century in Western society, a baby's gender did not so much influence the color of their clothes - they were often white - but the style. Infants younger than one year of age were often dressed exclusively in gowns. Afterwards, presumably when toilet habits were developing, the placement of buttoned openings distinguished the clothing between the genders. Girls had openings in the rear of the garments while boys had openings in the front. When young children's clothing was colored it did not have a significant association with their gender.
According to Wikipedia: "In Western culture, the practice of assigning pink to an individual gender began in the 1920s. From then until the 1940s, pink was considered appropriate for boys because it was the more masculine and decided color while blue was considered appropriate for girls because it was the more delicate and dainty color. Since the 1940s, the societal norm apparently inverted so that pink became appropriate for girls and blue appropriate for boys, a practice that has continued into the 21st century."
The current pink for girls and blue for boys was not uniform until the 1950s. After World War II, blue was used extensively for men’s uniforms. Therefore, blue became associated as more of a masculine color. From the 1940s onward, pink was pushed as a woman’s color.
Note - While researching for this, I found a series of dates associated with the conventions of associating of colors with gender. The earliest of these is a line in Louisa May Alcott's Little Women published in 1868. However is seems that the gender/color association wasn't common or uniform until many decades later.
