I don't know. We haven't gotten far enough into the game to start getting other women yet.
Regardless, I'm the wrong person to ask. I'm the type of player (and person) who always, always wants to deposit inside a woman and I don't like wearing protection. Plus, I love children and pregnant ladies, so.. I always, always go for impregnation on AVNs.
You can always just make a save point just before the choice to make her preggo or not. Then you can go with your favorite save for future updates and you have something to fall back on if she doesn't allow you.