my girl has about 12 rays to go and she is losing hair of her back end like in patches but does not go any further than the start of her stomach has any body any thoughts on this please also will it carry through to the puppies ?

If it's on her tummy then that's normal, bitches lose the hair around their teats when they have pups.

Bitches lose hair before whelping.  Otherwise, how would pups find the nipples...

its not on her stomach its on her back end near her tail also I do know they have to find the nipples its not my first litter

If it's along the spine it's normal, don't forget she would be casting hair now anyways.

V normal wherever it is.  Her hormones cause the hair loss.  It's greatest on the belly, but occurs all over.