Sciatica in late pregnancy/labor HELP

I've had sciatica bad already and it lasted a couple months before it went away ...and now it's coming back so I'm getting therapy again but I'm wondering how it's going to affect these last few weeks (3 to go!) and labor? Anyone had it this late in the game/during labor? I'm scared if it gets worse before it gets better again and I go into labor I won't be able to push.