Twins.... the 1 embryo split.

So they said Twin A has a heart rate of 145 and that's a strong heart rate. Twin B has no heart rate and is not viable. They are both measuring a week behind they're only measuring at 6w4d instead of 7w4d because they are sharing resources. So they said it's not entirely clear what is going to happen and I need to go back in 1 week and they want to see Twin A to grow a week's worth of growth and for Twin B to basically start to vanish.