[AVERYxo]

Originally Posted by Mardelin

The rule of thumb is not less than 5 pounds. But, more to be considered that just weight. 5 pounds on wee one, makes a wee one a fat yorkie. 4 pounds on a medium boned yorkie, she's skinny. More than anything is to make sure she's healthy, good bone, confirmation and comes from a line of free whelpers. Not always a guarantee that she'll be a free whelper, but why buy trouble by breeding a small one. The concern is not only being a free whelper, is she large enough to carry a litter of 5. If she's too small it can cause her to go into premature labor.
Do the measurement; if 3 fingers fit from the anal opening to the vaginal opening and 2 fingers fit between the pelvic bone, it can help you a bit in determining if she may be a free whelper.

Since breeding to improve the breed a breeder's main goal. One must look at your female critically.....Find a stud that will compliment her and/or fix her faults. So, it would be ideal that we all study genetics and take a few seminars on how to breed a better dog