There are a few cases of women dying as a result of solo erotic-breathplay documented in the book "Dark Dreams," by Roy Hazlewood. One is even a case where an African-American woman died of autoerotic asphyxsiation - apparently this was a first. It's a really good book with extensive coverage of autoerotic asphxia fatalities. I highly recommend it!
Actually, more than just a few women, and men have died as a result of loveplay gone wrong, asphyxiation being the main cause. There are even accounts of individuals causing thier own deaths while attempting to 'pleasure' themselves, and missing the mark by a couple of crucial seconds. There are quite a few serial killers who have reported an early facination with strangling and suffocation. The pain/pleasure patterns develop early on in some individuals, and as the personality establishes itself, the stage is set for a lifelong coupling of sex and death.....
And as the walls come down And as I look in your eyes My fear begins to fade Recalling all of the times... I have died. And will die. It's all right. I don't mind.
Oh, I'm sure there are a lot more actual deaths attributed to this than are documented - that's always the case! It's not my thing though - I'd be scared of accidentally choking someone to death...