twins, same sac, different gestational age?

I am 9 weeks and 5 days pregnant. I had my first ultrasound today and they found that one of the babies is right on track. The other one is only showing a 6 week gestational age. I was referred to another hospital for a different kind of ultrasound but my appointment is not for a few days. It looks as if the twins are sharing the same sac. I don't know what to think. Do one or both of the babies have a chance of surviving? If so, how great?

[Sanjivani Wanjari, MD]

HI,
When both the babies are in the same sac there are chances of complications taking place. The growth of one of the twins may be less than the other. Monitoring of the pregnancy with the help of serial ultrasound is necessary for follow up. Only time will tell how the babies do.
Hope this helps.