Pregnancy & Atenolol

I am 26 years old and was diagnosed with Supraventricular Taquicardia about 5 years ago. I have been taking Atenolol 50mg per day for the past 5 years. I recently learned that I am pregnant about 5-6weeks. I took Atenolol 50mg during this time because I was not aware of the situation. I called in to make an appointment with the gynecologist and also called my Cardiologist to see what I had to do. He said I should stop the medication asap, but my blood pressure began to rise and I have also heard  that it is not good to stop the medication all of a sudden. I was advised by a gynecologist to reduce my dosage to 12.5mg and that's what I've been taking until my appointment. Could my baby be born with birth defects because i was on a high dosage of atenolol during the 1st month?

[Yao Sun, MD, PhD]

There have been a few studies where Atenolol has been associated with birth defects or low birthweight, but the overall risk is still extremely low.  In general, the risk to the baby and the risk to you of reducing or stopping any medication requires discussion between you, your Obstetrician, and any specialist that is prescribing your mediation.  Obstetricians are very knowledgeable about the effects and risk of medications on a growing fetus.  You should continue your discussions with both your doctors about how to best manage your supraventricular tachycardia.