I think the most important thing is to have her talk to her doctor. They will really be able to help her figure out what is the best plan for her. There are so many factors that go into the decision, like how far along you are, what your health is like, etc.
Just as an example, I went to a local amusement park when I was early in my pregnancy (around 10 weeks) with my first DD. I had no risk factors, and the baby was the size of a shrimp. She cleared me to go on ANYTHING. Now, it was my first pregnancy, and it didn't seem like a big deal at the time, so I went on a double loop roller coaster! I probably wouldn't do that now, but at the time, I wasn't a bit worried. And it turned out fine! Baby turns 6 on Friday, and is a super smart and healthy kid.
Then a few years later, I was pregnant with DD #2 and going again. But I was much farther along. Still no risk factors, but that big belly wouldn't do too well in a seat belt. So doc had me skip anything with a height requirement of over 42 inches. I could still go on a surprising amount of rides, but no double loop coasters this time.
Anyway, that's a long way of saying that it really depends on the person and what their unique medical situation is. Have her talk to her doctor and see what she is healthy enough to do. If she has blood pressure issues, or pelvic organ prolapse, her options are going to be much more limited than a woman who still runs 25 miles a week during her 8th month.