Hi meowmeow... :-)
I had the same problem with my last pregnancy 33 years ago...and I was so afraid
I was going to miscarry.
I had an old gynecologist...he must have been 60 or so way back then...and he told
me healthy babies don't miscarry...and that every time I started spotting to lay down and prop my feet above my head with pillows.
I did that and even though I'd spot on occasion...never had a real problem...

Good luck..I'll be praying for you.....

How far along were you with the other 2 miscarriages? Have you ever been evaluated for an incompetent cervix? Ever had crysurgery on the cervix for abnormal cells? Have they considered doing a cerclage?