A bunch of the characters in the relations menu don't open because they're missing a sex name key, I'm guessing because I've been using the same save for a long time. I'll probably just figure out how to fix it with the console but if the Dev is here I'd suggest adding a check in that menu to populate the necessary key if it's missing.
Also, for those wondering pregnancy can be toggled for each character in the relationship screen after you finish the final event, and then the final event has scenes with them pregnant.