I went in for a second U/S at 8 weeks to see if Twin "B" has a HB and has caught up in growth. As it turns out, Twin "A" is measuring right on(8 wks 2 days) and Twin "B" has a HB(slow compared to her sister) but is measuring 2 weeks behind(6 weeks). My RE thought I most likely will miscarry her in the next couple of weeks and the chance of her survival is slim. My RE referred to it as the Vanishing Twin Syndrome. Please share your thoughts and experiences with me. I am trying to prepare for either outcome.