Delivering puppies is hard work, and it takes a while. You may have to encourage your dog to eat and take potty breaks.
According to Mar Vista Animal Medical Center, it typically takes about 45 minutes to an hour for a dog to deliver one puppy, including 10 to 30 minutes of hard straining. It's quite normal for a dog to take a rest partway through delivery. The mother will clean the puppies and eat their afterbirth. This process not only cleans up the little one but also stimulates his breathing, improves his circulation and allows mama to bond with her baby. She should resume whelping after a break that may last a couple hours.
You may have to coax mama from her nest by attaching her leash and leading her outside for a potty break. If that's the case, try to keep her normal bathroom schedule. It's important that your new mother keeps her nutrition and strength up, so she'll need to eat -- ideally puppy food -- while she nurses. If she's reluctant to eat, make sure food and fresh water are nearby so she can get nourishment and keep an eye on her babies. If she isn't eating a day after giving birth, contact the vet.