That's strange because my midwife said that theory of the 14p bpm was disproven. That doesn't mean she was saying sprint until you pass out. Make sure you can still talk while exercising but with how much a resting heart rate varies per person, I can't even imagine never exceeding 140 bpm.
Then again, I'm not an ob and you might have a history that made him say that. Just my two cents is all.
That's how I feel, especially if these are workouts that I've been doing for years. I am going to have a chat with my OB about it at my scan on Friday. Thanks for your thoughts.