How do Katherine and Blip know that the HoloDeck kills pregnant norns?
If you look at the story, you’ll notice that we never really see how the HoloDeck was programmed or put together or tested, we’re just told that it was. My own personal theory is that when Blip was programming it, he stumbled on some sort of bug (he could recognise it, he’s a machine) that would possibly kill pregnant norns. And then maybe he couldn’t fix it. Or something to that effect. Yeah, that’s the ticket. [The real reason is that it was in the first HoloDeck for some reason and I’m trying to keep some continuity.