The inhibition of pulmonary maturation in the fetal rabbit by maternal treatment with phenobarbital.

Phenobarbital was administered to pregnant rabbits, 7 to 10 days before the delivery of their fetuses at 27 to 30 days of gestation. There were no differences in body weight or wet or dry lung weights between control animals and phenobarbital-treated pups at similar gestational ages. The phospholipid content (PLC) of the alevolar wash was lower in the phenobarbital-treated group, but there was no difference in the lung tissue PLC between the treated and control groups. Phenobarbital-treated pups had higher opening pressures and fewer lamellar bodies than the control animals. These data suggest that phenobarbital may have an inhibitory effect on surfactant production and/or release.