In developing LFOS, I had to look closely at the code for woohoo and TFB. Without a mod, TFB is the only way to get pregnant. Well, there is the telescope, but let's not talk about that
If you want that risky woohoo behavior, you have three choices:
syberspunk's Risky Woohoo (MATY),
Twojeffs Autonomous Casual Romance (ACR).
There is a 4th option, but it's on a lot by lot basis, Lizzlove's Love Bed, which is also autonomous.