When I was pregnant with Nina, I told everyone it was just going to be DH in the room with me when I was in labour. When it come to the time though, I kept asking for my mum. I wanted my DH there as well, but my mum had been through this 3 times beforehand, she knew what I was going through, and I felt I just needed her there. Luckily she was in the waiting room.
The 3rd stage of labour happened so quick that by the time I delivered Nina, not only was my DH and mum in the room, but so was my dad and MIL! They waited in the corner of the room. No-one held Nina when she was born except me. They left within minutes of her being born, except for my DH.
I think you should leave your options open at this stage. Don't settle for not allowing your mum in just yet. You never know how you're going to feel until the time comes.