Here's what I do
I know my babies inside and out and anytime ANYTHING changes with them, I just know. I can tell when my female is coming into heat a week or more before she does. Of course I also have breeder software where I document everything as well.
My male wears a belly band (although this is not for preventing un wanted pregnancies) He has full roam of the upper level ofthe house. The girls have full roam of the lower level. My male comes and visits and steals their toys and chewys everyday.
When we are in heat, Brodie is only allowed to be around the female when they are breeding. We take seperate turns outside to potty and he doesn't get to visit. Its too stessful on him.
So far this is working out perfect for me. Although I know I'm not perfect and know there is that chance that on day a opps could happen to me. I just take every precaution to make sure it doesn't happen
Hope this helped!