Twin Pregnancy: Understanding Growth Discrepancies & Best-Case Scenarios

Question
At week 7 I was told I had a vanishing twin. Ten days later
the "empty" sack had a strong heart beat.At week 9 the
baby's both have strong heartbeats, but one is still a week
behind in growth. As it was a week before. I have two sachs
and 2 placentas. I'm worried about the small one. They
don't know why it is a week behind. What's the best case
scenario? I understand that there is a good chance of losing
the smaller one. But could I end up with 2 healthy babies if
it doesn't fall farther behind?
Thank you for your time,
Jamie Cleveland

Answer
It is very possible that both twins will do fine during pregnancy, even if one is lagging one week behind the other. Since there appear to be two placentas and two sacs, each baby is not dependent on the other one and there is less of a liklihood that there will be twin-to-twin transfusion. You do, however, have to understand that the smaller one may have some difficulties. However, if it survives rhoughout the pregnancy, it probably will be fine.