I can't be bothered trailing back through to find the post I made about this last time someone brought up scary premonition dreams, but to give you the quick(ish) rundown...
Baby #1 - Clear premonition-like dream that Mt Eden erupted and Auckland needed to be evacuated. It was soooo clear right down to seeing lava. John Hawkesby was giving updates on the tv and sirens were going off. (this was in 1995....no eruption so far)
Baby #2 - Clear premonition-like dream that my grandpa died. I could see Mum and I organising his memorial service and even him lying in the coffin. It was perfectly, perfectly clear. (This was last year and as far as I know - mum spoke to him yesterday - he's still living it up on the sunny gold coast with the rest of the retired NZers)
Baby #3 - Hubby needed to go to Wellington for a 4 day work trip - for the week beforehand I had really clear visions of the plane crashing. I could see the footage like I was watching a news bulletin and dreamed about the people knocking on the door from the airline to tell me that he had been in the crash. Really, really vivid. (Hubby actually went and came back with no complaints other than the seats were uncomfortable and there's not enough leg room).
Preggy hormones mix-up your brain to give you extremely vivid dreams that you tend to be able to remember. The anxiety that you feel about the upcoming birth and all the 'what-ifs' join in with this and it is quite common for women to have yukky, disturbing dreams about loved ones or their babies not making it. I think I can even remember someone having the EXACT same dream as you before she went on to have a gorgeous, screaming wailing little daughter of her own. (I'll hunt out the post).
The dream doesn't mean anything, just that you're normal(ish). If you are really concerned, hop down the road to Maternity Associates and get Margaret to work for her money and put the doppler on your tummy for a while.