Amy, doesn't that just make sense though?
Obviously a pregnant CF woman is going to be monitored much more closely than a non-pregnant CF woman. So if the doctors think she could have an infection, they're probably more likely to admit her than just send her home on oral antibiotics and Tobi. Also, a CF woman is considered a "high-risk pregnancy"--meaning she will have to go in for more check-ups, and more general monitoring than a non-pregnant one. This just makes sense, and is certainly not necessarily DUE to the pregnancy.
My mother has been an Ob/Gyn for 30 years, and she specializes in high-risk pregnancies. Neither her, nor four out of my five CF doctors have ever said CF and pregnancy don't mix (and this is my mother, who is paranoid about my health). I have had the "tie my tubes?" conversation with them many times and generally the answer is "no!". My PFTs are 60%, I am in the normal weight range for my height and my health is considered stable.
Though it may be more difficult to take care of a child when you have CF, it's more incentive to stay healthy for a long time. You can't just "give up" anymore because you're a mother. I think the happiness and love associated with having kids can only be a positive thing (unless you're maybe a single mom and don't have any kind of financial/emotional support network, in which case I think it would be quite difficult!)
Just my thoughts,
Chris