Atenolol Pregnancy and Breastfeeding Warnings Atenolol is also
known as: Tenormin Atenolol Pregnancy Warnings Atenolol crosses
the placental barrier and appears in cord blood. Administration
of atenolol in the second trimester of pregnancy has been
associated with the birth of infants that are small for their
gestational age. In addition, some data have shown a
significantly decreased fetal heart rate and significantly
decreased mean birth weight of infants whose mothers were taking
atenolol relative to those taking acebutolol or pindolol. Case
reports of profound beta-blockade in neonates of mothers who
were taking atenolol are reported. Because of this, observation
of affected neonates for bradycardia and hypotension is
recommended for 48 hours postpartum. The results of one study
indicate that maternal renal function, mean cardiac output, and
heart rate are significantly increased, while mean total
peripheral resistance is significantly decreased during the
second and third trimesters as compared to 3 mont