Yesterday my Obstetrician started me on a Beta Blocker (called Bisoprolol) due to me having a pre-existing heart condition and now having some cardiac symptoms and issues with my heart rate/rhythm. I'm 22 weeks pregnant tomorrow.
She told me a lot of women are prescribed beta blockers during pregnancy (typically for high blood pressure though) and not to worry. She said there were no risks to the baby's development but it can cause IUGR which will be monitored.
Unfortunately I'm a natural worrier so her reassurances haven't helped much 
Just looking to hear other people's experiences really...