fifteen weeks pregnant and have partial placenta previa. Help!!

I just found out that I a have partial placenta previa. Im worried that in might have the baby too early and it wont make it. dr. says it can move, but im a worry wart! I had three miscarriages in the past. I also have a ten year old son and no problems with him. Any thoughts or advice would help to ease my mind! thanks.
please.