* Age of the mother: Younger Yorkies tend to have smaller litters than older ones.
* Individual genetics: Some Yorkies are predisposed to having larger litters than others.
* Overall health: A healthy mother is more likely to have a larger litter than one who is unwell.
It's important to note: It's not uncommon for Yorkies to have litters of 1-2 puppies or even 6-7 puppies, but those are considered on the smaller and larger ends of the spectrum.
If you're considering breeding your Yorkie, it's crucial to consult with a veterinarian to ensure she is healthy enough to breed and that she is properly prepared for pregnancy and delivery.