GLUCOSE-HOMEOSTASIS DURING SPONTANEOUS LABOR IN NORMAL HUMAN-PREGNANCY

Using stable isotope, glucose turnover was measured in six normal preg nant women during the various stages of labor: during the latent (A1) and active (A2) phases of cervical dilatation, during fetal expulsion (B), and during placental expulsion (C). These data were com pared to measurements made in five postpartum women. Pancreatic hormones and co rtisol were also measured. In four other normal women undergoing spont aneous labor, catecholamines and free fatty acids mere measured. Plasm a glucose increased throughout labor from 4.0 +/- 0.2 (A1) to 5.5 +/- 0.5 mmol/L (C) (P < 0.01), compared to 4.7 +/- 0.1 in the postpartum w omen. Glucose utilization and production were increased throughout lab or at 33.4 +/- 3.1 and 32.8 +/- 3.1 mu mol/kg . min, respectively, com pared to 8.2 +/- 0.9 in postpartum women. Glucose metabolic clearance was also increased to 7.5 +/- 0.8 mL/kg . min compared to that in nonp regnant women (1.8 +/- 0.3). Plasma insulin remained at 59 +/- 5 pmol/ L during stages A1, A2, and B, but increased to 115 +/- 15 pmol/L duri ng stage C. Plasma glucagon was increased throughout labor at 127 +/- 7 pg/mL, compared to 90 +/- 4 pg/mL in control postpartum women. Plasm a cortisol increased during labor from 921 +/- 136 to 2018 +/- 160 nmo l/L, compared to 645 +/- 355 during the postpartum period. Epinephrine and norepinephrine also increased during labor from 218 +/- 132 pmol/ L and 1.09 +/- 0.16 nmol/L to 1119 +/- 158 and 3.61 +/- 1.04, respecti vely. It is concluded that labor is associated with a marked increase in glucose utilization and production. These findings suggest that mus cle contraction (uterus and skeletal) independent of insulin is a majo r regulator of glucose utilization during labor. Furthermore, the incr ease in hepatic glucose production could be favored by an increase in glucagon, catecholamines, and cortisol.