Well, this is something I never thought I would see - an animated film made by Walt Disney for Kotex, explaining menstruation. 

If you'll recall, back in the day, people were afraid to talk about periods. (To be honest, a lot of people are still afraid to talk about periods.) So, many companies would put out little informational videos and pamphlets (think those horrible videos you watched in Sex Ed. in school).

According to the poster of the video on YouTube, the film came out in 1946.

The 10-minute-long film features a bunch of cartoon women who look like Disney characters and offers sage bits of wisdom like, "Once you stop feeling sorry for yourself and take those days in your stride, you'll find it's easier to keep smiling and even tempered."