Natural ground is not safe for newborn puppies for multiple reasons. Firstly, the ground is cold, and with puppies not being able to move well nor properly thermo-regulate their temperature, it is a health risk. Secondly, it is not a clean area for your puppy to be. The ground can be dirty and soiled and this could lead to the spread of bacteria affecting your puppies. Finally, the hard ground can actually lead to your puppies' bones and spines becoming deformed as they are so fragile after birth.