The gestation period for a dog, regardless of its breed, is about nine weeks, or two months. A dog's pregnancy can last from 58 days to 68 days, with the average being 63 days.
Gestation length in dogs is calculated from the day their eggs are released to the day of their puppies' births. Dog pregnancies consist of three trimesters of approximately 21 days per trimester.
Although gestation periods are uniform for all dogs, onset of puberty is not. Smaller breeds tend to begin heat younger, at about 4 to 6 months of age. Larger dogs can start as late as 24 months.