When did we start using blue for boys and pink for girls?

When I was pregnant with D, I was unprepared for the onslaught of "is it a boy or girl?" excitement from nearly everyone I encountered. I tried to breezily dismiss questioning about gender reveal cakes and nursery colors by quoting Graham Chapman's surgeon from Monty Python's Meaning of Life: "Now I think it's a little early to start imposing roles on it, don't you?"

But historically, it is novel to know a fetus' sex with near-certainty. The notion that you could see the fetus at all, let alone determine its sex, was impossible if not unimaginable until sonograms emerged in the 1950s. The same tool that monitors the health of a growing fetus throughout a pregnancy is now used to categorize its sex at around 12-13 weeks, which leaves expectant parents with roughly 28 weeks to outfit a nursery in an "appropriate" color and fill tiny hangers with pink or blue clothing. 

Of course, this opportunity has been seized upon by retailers who stand to benefit from expectant parents and well-wishers purchasing separate sets of nursery furniture, toys, and clothing in gendered colors. But what's especially surprising is how new that gendered color code is. For Pink and Blue: Telling the Boys from the Girls in America, Jo B. Paoletti studied clothing catalogs, baby books, and even paper doll collections from 1885 to 2011, and found that the gendering of pink for girls and blue for boys is remarkably new, given its ubiquity. Up until the 1900s, Paoletti writes, most American babies wore simple white gowns, easily removed and bleached when needed. In the middle part of the 20th century, the color code was actually the reverse of what we know now, with pink the predominant color for boys and blue the predominant color for girls. 

So if you're looking to be traditional with respect to baby clothing, just buy a few white gowns (or perhaps a stack of white onesies) and dress all of your babies in them. To defy more recent traditions, dress your boy in blue. If you want to defy current gender norms, opt for the pink.