I don't think i got my rhogam shot after last delivery of 3rd child (did w previous 2 births). now pregnant again. will i miscarry baby?!

Unlikely: If you miscarry, it is likely not related to the Rh problem. Usually the first pregnancy after a missed Rhogam results in fairly mildly hemolytic disease, but subsequent pregnancies have increased likelihood of hydrops. Be sure your OB is aware of your situation, and your baby will be monitored carefully. Your baby may need phototherapy or exchange transfusion after birth.