You don't always have bad cramping or bright red blood. In July my baby died around 9 wks and I went on to carry it until 16 wks before I started having symptoms of a m/c. I was just having brown spotting, plus I had an ultrasound at 6.5 wks and the baby was fine with a nice strong heartbeat, so my doctor wasn't concerned. I went on for 7 wks thinking that me and my baby were fine because I wasn't having any bright red blood or really bad cramping. It finally started at 16 wks. I had blood and cramping so I went for an ultrasound and that's when they found out that my baby had died 7wks before, my body just didn't want to pass it on it's own.
So yes, there can be spotting and cramping but it is not the same for everyone. For me it didn't start for a really long time. I always tell women to trust their instincts, if something doesn't feel right to you then go and see your doctor!!