Very interesting.  Some of the articles I had previously read about it, which I will quote below for anyone interested in more than my bad paraphrasing, mention that it finally switched in the 1940’s but I had never seen Hitler before as the direct source of this.

“When the color assignments among boys and girls did evolve in the ’20s, the colors were reversed: pink was for boys and blue for girls. It wasn’t until around the 1940s that the colors flip-flopped to the assignment we recognize today [source: The Guardian]. This lends support to the notion that the color preference between pink and blue comes from culture rather than biology.”

Source: here

And further, if that isn’t enough:

“(in 1918) the Ladies’ Home Journal wrote: “There has been a great diversity of opinion on the subject, but the generally accepted rule is pink for the boy and blue for the girl. The reason is 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.”

source: here

So if anyone has a link to the Hitler theory I would be interested in actually reading it- I had difficulty finding anything.

“After WWI, blue was used extensively for men’s uniforms. Therefore, blue became associated as more of a masculine color. From the 1940’s onward, pink was pushed as a woman’s color.”

source: here

I also read this, which seems to suggest that rather than creating the pink=femininity, Hitler was actually just playing off of it:

“What prompted the switch is unclear, but it had been made by the time Adolf Hitler ordered the classification of homosexuals. Those deemed “curable” were sent to concentration camps and labelled with a pink triangle. This suggests that by then, pink was associated with femininity.”

source: here