A "multiple pregnancy" is twins, triplets or more. Not your other children. Did you get the news that you have one? Oooh! Way cool.
I just read your post below and can see that you were asking a follow-up question to a comment. I am so very sorry for your loss of the twins. I would definitely ask the doctor about having a cerclage (the stitch she mentioned) after having had a loss based on your cervix opening too soon. Again, I'm really sorry about your twins, and hope you will realize I didn't know what had happened. Good luck getting pregnant again!
ps -- You can post follow-up questions on the same post that you asked the original question. At the top of the comment box there is even a place to write the name of the person you are writing to in particular. That way, the person who wrote to you can find it easily.