Yesterday on my 47th birthday I took a pregnancy test "just to rule it out" as I had waited a while for my period to turn up thinking it was the start of peri. And... it was positive with weeks indicator saying 3+ (so no chance of the false positive menopause thing, the level of hCG is far too high). Never been pregnant before.
It's quite a shock, although not an accident. I had pretty much resigned myself to being childless but still held out some hope. Long story short, I thought I didn't want kids, until I met my current partner a few years ago and changed my mind. We've been TTC on and off thinking it was probably too late.
It would be good to hear from other expectant mothers in late 40s - first time or otherwise - just to know you're there really, cos it's all feeling totally surreal right now!