Because of atenolol's relatively extensive excretion into breastmilk and its extensive renal excretion, other agents may be preferred while nursing a newborn or preterm infant or with high maternal dosages.[1,2] Infants older than 3 months of age appear to be at little risk of adverse effects from atenolol in breastmilk. Timing breastfeeding with respect to the time of the atenolol dose appears to be of little benefit in reducing infant atenolol exposure because the time of the peak is unpredictable.[3]