I had sciatica too for second pregnancy. It was pretty bad from second tri till I give birth. I had to endure the pain. Didnt do any PN Massage till I give birth. You are highly advise to do PN Massage from 4 to 5 months onwards.
It is common for most mum to have sciatica esp on the left side.
If you dont do PN/PP Massage to reduce sciatica pain, it will get worse esp when you want to walk, seat or stand.