Many people don't have a clue in regards to how long dogs will be pregnant for before giving birth, and many of whom may have dogs that are in fact pregnant! In short, it varies, as smaller dogs will stay pregnant for a shorter period of time. Typically, it can be expected that a dog will be pregnant from 55-60 days, or 8-9 weeks. However, you will want to look up your specific species to find out when exactly they will be expected to give birth.