A pregnant dog gives birth approximately 63 days after conception, according to PetMD. During this time period, the dog's body prepares for birth by stimulating milk production.
According to The Daily Puppy, a dog's abdomen tenses when it begins the labor process. These are contractions allow the puppies to emerge from the dog's womb. The frequency of these contractions increases over the course of the labor process, until the puppies are born. Once the first puppy emerges from the womb, the following puppies normally arrive within 20 to 30 minutes. In some cases, puppies may arrive several hours apart from one another.