Cranberry for fluid retention during pragnancy?

Has any one had any experience with this. My darling is 6 weeks pregnant today and I read it somewhere that cranberry helps with fluid. My last litter was 5 pups and the vet said they were expecting about 8 for the size of her. Her sister had her pups taken a week early because she had a lot of fluid and it was pressing on her uterus. She had 8 pups and all but 1 died. I don't know if it was a direct result of the fluid or something else. It's just freaking me out.
Thanks