I tried going for a bizarre run recently to see what I could find. It started as a Jake run because I realized ever since the permanent Jane option was added to the game I haven't tried anything with Jake in the newer days. As I was going the run became more of a 'who can get pregnant from others' run. What I found is a lot of these instances happen later in the game so at first I thought there would be no preg talks at all, but then I remembered Jake can knock up Sofia early in the game via the bimbo route. But to my surprise I didn't get the Sofia preg talk, maybe it was considered too late by a day or two, or you can only get preg talks if it's yours, I'm not entirely sure.
It was definitely an interesting run however on the last day I noticed something that might be a continuity bug, I got Jake to get his mom pregnant in the new scene, then I did the last DnD segment and found there was a opportunity for Jake to knock up his mom here. I never knew that before because by this point he would always be Jane. However when he came inside her the game went into detail saying she was already pregnant (yes) but that it was the players (no), and I know I made sure she wasn't pregnant before Jake got his chance in the new scene.