I'm aware that when baby clothing was initially designed for each gender, pink was considered the masculine color and blue the feminine color, but obviously that perception has completely reversed.
I've read articles which say the change happened around the 1940s, but I couldn't find a good reason why. I'm just curious how such a perception could be completely turned on its head.
There is actually a great book on the subject: Pink and Blue: Telling the Girls from the Boys in America, Jo Barraclough Paoletti, 2012.
It's a misperception that the colors used to be rigidly defined as pink for boys and blue for girls: different publications and etiquette books gave different instructions. Some said that, some said pink-girls/blue-boys, and some said to put all infants in pastels - it was simply a matter of aesthetics and justifying them, rather than a real system of gender coding. White was more commonly seen on children of both genders from the 1770s through the 1920s, because until toddlerhood there was no differentiation between girls' and boy's clothes. (Male toddlers were still in dresses, but by the late 19th century there were specifically "boy's dresses" - a little plainer and shorter.)
Over the course of the early 20th century, the unisex white dresses for infants grew shorter and dresses were less frequently made for male toddlers. This coincides with the gradual concretening of the assignment of pink and blue to girls and boys, respectively, and with an increasing amount of marketing. Advertising was a huge part of this process, as Paoletti notes. You can sell more clothes and toys to parents with multiple children if they feel they can't reuse them between boys and girls.
hi! you may find more of interest in these posts
Why did pink become girly? - /u/cecikierk suggests it was blue ribbons for baby Prince Charles in 1948
Why is pink associated with girls and blue associated with boys? - the Smithsonian Magazine suggests advertisers in the 40s