It depends on the genetics. Yorkies come in all sizes, male & female.
The male must always be smaller when you are breeding.
That's what I have been told. Princess is going to breed in her next heat,
she's in heat right now, but just turned two, and I rather wait till the fourth heat. She's 4 1/2 pounds, her mate is 2 1/2 pounds, he's so small, I hope he can reach!
Hope you have a nice day!
Gina & Princess