SummaryStudies of maternal metabolism during pregnancy have focused principally upon the latter half of gestation. However, maternal metabolic adaptations to pregnancy may occur at all stages of pregnancy. To study maternal metabolism throughout pregnancy, we developed a chronically catheterized rabbit model in which animals could be studied under conscious, stress-free conditions when nonpregnant and then serially throughout pregnancy.Anesthesia produced marked hyperglycemia. In contrast, chronic catheterization and daily handling did not affect blood concentrations of glucose, lactate, ketone bodies, or free fatty acids, or food intake. Glucose concentration decreased with pregnancy to a value at term equal to 85% of the prepregnancy value. Lactate concentration rose significantly in the second half of pregnancy but changes in free fatty acids and ketoacid levels were not significant. These results are discussed from a comparative physiologic point of view, emphasizing the unique aspects of rabbit metabolism during pregnancy and the importance of performing such studies under conscious, stress-free conditions.