Pregnancy themes appear in a few Bad End scenes. You can unlock these for viewing at any time by beating their related encounters... or by losing to them, but this may cut your journey short!
There is no impregnation/pregnancy/birthing content outside of these scenes, given the scope of the game and the limited timeframe in which it takes place. you're well catered for, however: at a rough count, I think at least five scenes contain breeding as a theme.