Usually a Chihuahua puppy will be born every 30 minutes or so, following 10 to 30 minutes of forceful straining. However, it is possible that the mother could go on for up to four hours between pups.
Some time after the last pup has been born, she will expel the placenta and any remaining blood and fluids, which may look like urine.
During the last few weeks of her pregnancy be sure to crate your Chihuahua when you can't watch her. If a puppy is born and she is in pain, she may try to bolt which can seriously injure the pup. Also, if alone and frightened she could give birth in different locations, so the pups will be cold and in danger and she will panic.