You guys must have either really big yorkie girls or big puppies.... my girls gain around 1 - 2 pounds... their puppies range between 2 to 5 ounces. The average litter size is 4. My Wilma and Lucy recently had 2 pups each... they probably gained a little over a pound each... which on a 5 pound yorkie is alot. (3 pounds????.... my girls would be dragging their tummies!!!).
I think the weight gain must vary with the size of the mom and the number of pups.
Best of luck with Madie's pregnancy!!!