All dogs, regardless of the breed, should not be bred until they reach sexual maturity around 6 months to 24 months for a female dog and around 12 to 15 months for a male dog (though male dogs can be fertile as early as 6 months), according to the AKC. To register a litter of puppies with the AKC, the mother must have been at least 8 months old and the father must have been at least 7 months old.

It is also recommended that the female Yorkie not be bred during her first heat cycle. Before Yorkies are bred, each dog should be taken in for a physical examination by a veterinarian to ensure that they are healthy enough for breeding.