I finally got my first ultrasound and I was told that it is suppose to be a twin pregnancy. They told me baby a is strong and healthy, but they can't find the baby b in the second sac. The doctor said because the babies are different ages (one is at 7wks, one about 6wks) that baby b could just be hiding behind baby a. But I'm so scared that I already lost baby b. Has this happened to anyone elese? And If so, did your baby b make it?