Endothelin receptor antagonist has limited access to the fetal compartment during chronic maternal administration late in pregnancy

Maternal administration of an ETA antagonist, at a dose sufficient to ameliorate FGR, has no adverse impact on survival and growth of neonatal rat pups. ETA antagonism, delivered maternally, produces sufficiently low fetal plasma levels of antagonist so as not to present a survival threat to the neonatal pups. The beneficial effects of maternally administered ETA antagonism on fetal growth occur in the maternal, not the fetal, compartment.