ADRB2 and fetal growth restriction: Specifically, acute fetal normoxia improved insulin secretion in the IUGR fetus prior to reductions in circulating norepinephrine (Macko et al., 2016), and daily maternofetal oxygenation of IUGR pregnancies late in gestation improved post-natal skeletal muscle growth and metabolism without recovering Adrβ2 content (Cadaret et al., 2019c).