Miscarriage Question

I am 5 weeks today. My first ultrasound isn’t until September 25th which would be my 9 1/2 weeks point. My question/concern is if my baby were to become unviable (heart stop, genetic issue, etc) would my body recognize this and terminate the pregnancy on its own? So, as long as I don’t have heavy bleeding, or miscarriage symptoms from now until then, I can assume everything with baby is ok? Or for example, could my baby be unviable next week, and I wouldn’t know until my 9 week scan?