Effects of maternal insulin or glucose infusion on the fetus: study on lung surfactant phospholipids, plasma myoinositol, and fetal growth in the rabbit.

Pregnant rabbits were given continuous intravenous insulin between days 26.7 and 28.7 after conception. The treatment decreased fetal serum glucose, insulin, and myoinositol. Furthermore, maternal insulin decreased fetal growth slightly, and improved the survival of the prematurely delivered fetuses. Analysis of phospholipids recovered by alveolar lavage revealed that the lung surfactant was quantitatively and qualitatively superior to the surfactant from the fetuses of the saline-glucose control animals. This effect on the lung was more striking than that of glucocorticoid. Another group of pregnant rabbits received continuous intravenous glucose between days 27.0 and 29.0 after conception. The hyperinsulinemic fetuses of the glucose-infused does weighed more and had higher serum glucose and myoinositol than did those of the control animals. There was no detectable difference in alveolar lavage phospholipids between hyperinsulinemic and normoinsulinemic fetuses of glucose-infused does. The possible importance of these findings in understanding the mechanism of acceleration of lung maturation is discussed.