If your dog is going to have puppies, you need to provide her with a whelping box so she has a safe place to deliver them.
Description of a Whelping Box
A whelping box, or nesting box as it is sometimes called, is essentially the place where your dog will deliver her puppies and raise them for approximately the first six weeks of their lives.
Every whelping box should have a bottom and four sides. The sides should be approximately 12 to 18 inches high, with a lower opening at the front that makes it easy for the bitch to get in and out of the box. Ideally, the box will have an inner rail that runs around all four walls and is set approximately four inches above the bottom of the box. This rail prevents the mother from accidentally pinning a newborn puppy against a wall and smothering it.