Atenolol and Pregnancy: Risks & Safety for Mothers with Hypertrophic Cardiomyopathy

Question
My daughter has her first prenatal appt June 1.  First day of her last period was March 27, she has an ICD, hypertrophic cardiomyopathy and takes Atenolol - 75 mg.  This is her 2nd child.  Her first pregnancy was high risk because of her heart, cardio said with ICD she could have other children, but would have same risks.  She is planning a tubal ligation when this child is born.  Our question is the affect of the atenolol on her unborn child...what affects could there be?  

Answer
Atenolol is a cardioselective Beta adrenergic blocking agent used for the treatment of hypertension. The drug did not cause structural anomalies in pregnant rats and rabbits, but a dose related increase in embryo and fetal resorptions in rats was observed at doses up to and greater than 25 times the maximum recommended human dose. It is a category D medication, which means that there is positive evidence of human fetal risk, but the benefits from use in pregnant women may be acceptable despite the risk in a life threatening situation or for a serious disease for which safer drugs cannot be used or are ineffective. Atenolol readily crosses the placenta to the fetus. The drug may result in Intrauterine Growth Restriction. The reduced fetal growth appears to be related to increased vascular resistance in both the mother and the fetus and is a function of the length of drug exposure.  Although  growth restriction is a serious concern, the benefits of maternal therapy with atenolol may, in some cases, outweigh the risks to the fetus and must be judged on a case by case basis.