my bitch is pregnant, due to have her pups any day, she had 12 pups last year and all went well, although it was hard work it was very rewarding, howver she would eat the puppys stools, is this normal and can it cause her harm, if its normal how long should she be allowed to do it for.

This is normal behaviour. My bitches usually stopped when I started weaning the puppies (at about 3 weeks). The more you clean up after the pups, the less the bitch will need to do it.
:)
Edit: Remember, you'll need to worm her at the same time as you worm the litter.

Hi Sian, it's completely normal. She'll certainly do till you start to wean the pups, and probably quite a while longer. It's all part of nursing her babies.

Dawn R.