S.D.
I would tell her to take it. The benefit outweighs the risk in her case. I read the other responses, and I too am a nurse, so this is coming from a nursing standpoint as I have never had high blood pressure. If her blood pressure gets too high she could have a stroke which would affect her and the baby. She could also end up in the hospital on IV drips (med continuously infusing) until they can control her blood pressure. Again, this would affect her and the baby. High blood pressure on it's own, even if she doesn't have any issues from it will affect the blood flow to the baby and restrict it's growth, possible causing a premature birth or low birgh weight. Again, I would strongly urge her to take the med. I myself take seizure meds, so I know what it's like to not want to take the meds while pregnant, but like I said before, the benefit waaaayyy outweighs the risk. Has she discussed not taking her atenolol with her OB & regular doctor?
Good luck and congrats on being an Aunt!