In a just world, nobody would have to work when pregnant if they didn't want to. Unfortunately, that's not the world we live in, and in the good old U S of A it's not uncommon to see women grinding until they pop.
Companies and managers aren't always sympathetic to the struggle, either. This is what one school administrator found out the hard way when the health issues she was experiencing in the last weeks of pregnancy led her to make a request to her supervisor to work from home until she gave birth. When this was denied on the grounds that it was one of the busiest times of the year, she knew it was time to enact some malicious compliance.
It's fair to say that all Redditors felt like this revenge was 100% deserved. That manager was lucky that she didn't go into labor in the workplace just to please them.