I think LoveForPits has it absolutely right. You also need to be prepared for major behavioral changes in the ***** if she does become pregnant. Sometimes her behavior will do a complete 180 before she even begins to show. I've been called in for normally docile dogs who were "leaking" urine uncontrollably, biting or snarling, hiding away, nesting (long before it was time), etc. and it turned out the poor thing was pregnant! Most dogs don't go completely nuts, but it's something you need to be aware of.
Also, remember that the farther a breed gets from the physical "doggy ideal"--meaning a wolf--the more hereditary health problems that breed is likely to develop. (Think of Bulldogs, Great Danes, and Pugs, and the sort of genetic problems they experience.) Doxies are about as far as you can get physically from a wolf--back problems, blindness, luxating patellas, ear infections, hernias...you name it, they can be born with it! Even with a clean bill of health for the male and the female, it's very hard to predict which recessive genes may manifest in the pups. So you need to be prepared to make the decision that may arise; are you willing to pay for a pup's surgery, should he or she need it? Or would you have to euthanize him? That can be a really difficult choice.
And just as Renee said, with Doxies (especially minis) you have to plan for a cesarian section. Frequently the pups are just too big to move through the birth canal. This, as any surgery, poses health risks to the mother and the pups.
Now that I've gotten all my doomsaying done, if you do decide to go ahead with it, I wish you the best of luck.
