Hepatic lipogenesis and ketogenesis in the mother and fetus during postmaturity in the rat.

Prolongation of pregnancy for 1.5 days by the injection of progesterone leads to a decrease in maternal liver glycogen content and an increase in blood ketones without alteration in the activity of hepatic hydroxymethylglutaryl-CoA synthase, an enzyme of ketogenesis. Fetal hepatic mitochondrial hydroxymethylglutaryl-CoA synthase activity increases with increasing postmaturity in a similar manner to that observed in normal neonates, suggesting that the factors necessary for enzyme induction are present in utero during postmaturity and that birth and the intake of the milk diet of suckling are not essential for increased enzyme activity. Hepatic in vivo lipogenesis is elevated in both mother and fetus during prolonged pregnancy and the results indicate that progesterone may have a specific effect on hepatic lipogenesis.