Im currently 12 weeks pregnant with a yeast infection, why are people saying to use Monistat 7 over Monistat 3?

I usually use Monistat 3, I’ve been using that before I was pregnant to help with yeast. My primary says Monistat 3 or 7 is fine during pregnancy. I wanted to know why women are saying to use only Monistat 7 instead?