I would probably suggest not using it postpartum, just because it might increase the risk of infection. I think that postpartum, it's better to let things come out completely - even though it's a big PItA.
However, this is just one opinion and definitely isn't the end all. After all, I hardly bat an eye when couples resume intercourse within the first week after birth. I guess it all depends on how you feel and how heavy your flow is, etc.