*IN GENERAL*, unless the dog is hung like the proverbial horse and routinely bashes against her cervix during mating (not impossible, but not all that likely, particularly with a rotty - they tend toward the "shorter and thicker" part of the scale compared to other breeds, at least in my experience) or there's some complicating factor, letting the dog mate with her is unlikely to have any bad effect on the pregnancy. At 2 months gone, the changes in her body are going to be so small that for practical purposes, the fact she's pregnant can pretty much be ignored. As the pregnancy advances, the changes will become more significant, and might pose difficulties as far as letting him mate with her. Toward the end of the pregnancy (last 8 weeks or so is a reasonably good ballpark figure, but will vary from one woman to the next) she may find that letting him mate with her is uncomfortable. If, at any time, she does feel discomfort from being mated, it's probably time for her to stop until after the kiddo comes out to say "howdy". Aside from that... <shrug> The old line "if it feels good, do it" comes to mind. Compare the dog's penis size when he's fully erect and squirting to your own size when you're about to mate with her yourself, and if the two of you are reasonably close in size, you can apply the doctor's advice about sex with you to sex with the dog.
Please note that I said *IN GENERAL*. I ain't a doctor, I don't play one on TV, and I didn't stay at a Holiday Inn Express last night...Things I don't know about her particular situation may exist that could make everything I say a complete stack of bullshit for her pregnancy.
