Miss

what cause bleeding on the 8th week of pregnancy and termiantion

[Clysta]

Typically it would be a chromosomal issue with the child that would have made it incompatible with life outside the womb.

[AnnieBrooke]

I am sorry for your loss.  Unless testing was done on the embryo, there is no way to know, but it is almost always that something did not meet correctly 'way back the day the sperm met the egg, and then when that thing was needed, the embryo's development stopped.  It is almost certainly nothing you did or didn't do.  Bleeding is caused by the loss, not the loss being caused by the bleeding.  Rest, repair, and try again if you are so inclined.  Good luck.