I play each pair & birth by ear.
Some I leave until the birth,some dames just won't let the males handy anyway, while some Dads seem help keep her calm.Some hate to be separated.
If Dad is getting antsy as Mom gets close to delivery I take him out. She needs her rest, and having Dad chasing her around is to taxing.
First litters I take him out most always. Maybe a week before LOL Like I said play it by ear and do what ever you feel comfy with.
Some pop them out faster than I can get him out too.
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Another good point, I just had one go in heat and mate 6 weeks after delivery. They were all in the cage together from about day 10 after the birth. That's never happened to me before. :-[ If I'm keeping them together I just let the mate at the 8 week heat, but this one at 6 weeks. I'm still not sure she is pregnant again.