I'm trying to prevent pregnancy in my inactive ancestral houses but premit pregnancy in inactive nonancestral households is it possible for me to make them infertile or just not allow pregnancy all together for them??

I think you need nraas Storyprogression for this and either with Castes or disable it for any lot (and household)
or forbid it for the town and allow for active household as an example.

You can only end or pause the pregnancy with MC

Sim - Advanced - Pregnancy
MasterController-Interactions#End-Pregnancy