Worms can show up in the eggs, it's not common or usual but it can happen. And no, pumpkin will not deworm your birds. You could gather up several poop samples and take them to a vet to have them tested for worms if you'd rather not deworm at this time. Otherwise a regular deworming schedule...
I have a couple with extra fluffy backsides that need the occasional trim to keep things tidy. Sometimes worms can cause a dirty behind as well. Something to consider if they haven't been dewormed.