This person evidently thinks she is an expert on Yorkies. I have read page after page from her site and I'm just shaking my head. This page made me laugh out loud.
Secret Methods Used By Yorkie Breeders To Get The Best Results
The Fourth paragraph reads.
"It can be very hard on the body of such a small dog to have litter after litter.
Therefore they limit it to a couple of pregnancies per year. This will likely yield between four and six puppies per year."