Canine pregnancy moves a lot faster than that of humans. Each week of their pregnancy can encompass a lot of new symptoms as they prepare for a litter. Yorkie pregnancies in particular should be watched carefully as they are a smaller breed; make sure you consult with your vet and try to take your dog to a clinic, if possible.
Early Signs of Pregnancy (1-4 weeks)
The stages of canine pregnancy are blurred as the pregnancy extends between 58-65 days on average for Yorkshire terriers.
Early signs your dog may be pregnant before you can confirm this with an ultrasound at four weeks include: fast nipple growth or appearance, she'll be less energetic, more affectionate or clingy, mood swings, her stomach will expand and firm, she'll clean herself more than normal and may attempt to gather items and build a nest. These symptoms can appear very early. In the first few weeks of pregnancy try to give her the usual amount of exercise, and keep a careful eye on her.
Mid to Late Pregnancy (5-9 weeks)
At 28 days of pregnancy a vet will be able to confirm by checking the palpitations if pups are present, however an ultrasound is more accurate. By Week 5 you should be increasing her diet and feeding her puppy food which provides her extra calories; lower the amount of exercise you give her, you won't want her jumping or playing rough at this point as the puppies are nearly completely developed. During Week 7 she will feel them moving around and you may be able to as well!
As she gets closer to her due date create a "whelp" box for when she gives birth if you plan to help her have them at home. During weeks 8 and 9 she will try to nest and rearrange her box and you should feed her several small meals a day. She won't be comfortable towards her delivery day so don't be surprised if she isn't acting herself.
Whelping (Delivery) of Puppies
The last stage is the actual delivery. According to the Yorkie Info Center, delivery of Yorkies really should occur in a clinic unless you have experience as a breeder.
When her temperature drops under 100 degrees Farenheit she will birth puppies within 24 hours. She may begin to vomit or cry; just be prepared to comfort her. Make sure your whelp box has an opening on one side for you to help her and lots of newspapers to help make it easier to clean. She will experience contractions leading up to the birth of her litter.
Once her water breaks puppies will be pushed out in a sac consecutively within a two-hour span of one another at most. She will break open each sac and clean the puppy herself and may even eat the umbilical cord as it is her natural animal instinct. She may eat the placenta which will emerge after all the puppies are out.
If birthing at home and she does not start labor within 24 hours of her temperature drop, no puppies have come out despite her showing extreme pain, crying or vomiting, or you believe there are more puppies after the two hours since she birthed the last pup, contact an emergency vet immediately.