I definitely know what she is experiencing. At that point everything is physically more difficult and mentally it is hard to get your self up for something that's not really all that enjoyable anymore.
I ran up to 36 weeks during my first pregnancy. Albeit, it was very SLOW. My husband could walk faster than I was running.
I didn't have much pain but just felt out of sync and sluggish. Part of the problem could have been I put 37 pounds on a small frame.
To get through the runs I alternated running with walking which made it much more reasonable.
I also had contractions while running from time to time. My OB said it was ok as long as there weren't too many. Whenever I experienced a contraction I immediately stopped and walked for a bit.
I ended up quitting at 36 weeks mainly because I got mentally tired of everything - pregnancy, running, being huge, etc. I chose to sit on the couch and be a grump for the final weeks :)