I love my mum, she is awesome, and I'm sure she'd be great at a birth - she was an NCT teacher for years so was birth partner for several of her tutees for various reasons. But I don't want her there at my delivery (due in just under a month).
Firstly, she lives 2 hours away, so I don't want her racing down the motorway or to have to worry about why she hasn't arrived yet.
Secondly, while I have no doubt she was a great NCT teacher, I'm an anaesthetist, so our perspectives on certain aspects of childbirth are somewhat different. I don't want to have to discuss e.g. epidurals in depth when in labour - if I decide I want one then that's final!
Thirdly, I just don't want to have to deal with more people than is necessary. Not to do with nudity etc, and I have no issue with endless HCPs being there, but I want to be able to find my own "zone" and deal with things my way, and the fewer people I have around, the better. DH will be fine, but I don't want to worry about anyone else there.
FWIW, in my professional capacity I go into a fair number of delivery rooms, and I'd estimate that a significant number, but less than half, of women have their mothers there, so either way is definitely not abnormal!