The slave guild abortion and miscarriage potion both use the abortion function. Any attempt at removing a pregnant slave from the mansion results in them using the abortion function. Thus all 3 cases call the same function that was the cause of the old pregnancy resets bug, which in Strive v1.0d results in crashing as the game is no longer running in debug mode. So unless you have already implemented the fix yourself, this is the cause: https://itch.io/post/2931544 The Bugfix mod attempts to clean up loose ends by not keeping unnecessary data, which in this case is babies that will never be born.
Edit: just woke up and overlooked a call of abortion function