Hi, I'm 12 weeks pregnant with DCDA twins, spontaneously conceived, or at least I might still be. A viability scan at 7 weeks showed two, one twin doing well for dates with a heartbeat but the other two weeks behind. I then had a scan at 9 weeks which showed that while twin 1 was still doing well with a good heartbeat the other was still not progressing, had a heartbeat but really slow, and the sac was collapsing. So, I'm resigned to my next scan next week showing the 'demise'of the littlest one and feel sad about it but philosophical I guess 
But I'm wondering how long it might take for the vanishing twin to vanish at this point? I'm concerned for umpteen reasons about the surviving one (if it survives...) I've already been told I can't have the harmony test because the results will still take on any likely chromosomal issues in the vanished twin - I'm 40 and feel the pressing panic of the possibility that I'm high risk of any number of abnormalities and issues, I am imagining that I'll be offered invasive testing which comes with it's own issues obviously...
Don't know what I'm asking really, just if any twin mums (or multiples) had this happen and what was the outcome?