Uteroplacental Glucose Uptake and Fetal Glucose Consumption: A Quantitative Study in Human Pregnancies

Abstract

Context Maternal glucose levels and body mass index (BMI) are determinants of fetal overgrowth, but their relation to fetal glucose consumption is not well characterized in human pregnancy. Objectives To quantify uteroplacental glucose uptake and the allocation of glucose between the placenta and fetus and to identify factors that affect fetal glucose consumption. Design Human in vivo study in term pregnancies. Setting Oslo University Hospital, Norway. Participants One hundred seventy-nine healthy women with elective cesarean section. Interventions Uterine and umbilical blood flow was determined using Doppler ultrasonography. Glucose and insulin were measured in the maternal radial artery and uterine vein and the umbilical artery and vein. In a subcohort (n = 33), GLUT1 expression was determined in isolated syncytiotrophoblast basal and microvillous plasma membranes. Main Outcome Measures Uteroplacental glucose uptake and placental and fetal glucose consumption quantified by the Fick principle. Results Median (Q1, Q3) uteroplacental glucose uptake was 117.1 (59.1, 224.9) μmol min-1, and fetal and placental glucose consumptions were 28.9 (15.4, 41.8) μmol min-1 kg fetus-1 and 51.4 (-65.8, 185.4) μmol min-1 kg placenta-1, respectively. Fetal glucose consumption correlated with birth weight (ρ: 0.34; P < 0.001) and maternal-fetal glucose gradient (ρ: 0.60; P < 0.001), but not with maternal BMI or uteroplacental glucose uptake. Uteroplacental glucose uptake was correlated to placental glucose consumption (ρ: 0.77; P < 0.001). Fetal and placental glucose consumptions were inversely correlated (ρ:-0.47; P < 0.001), but neither was correlated with placental GLUT1 expression. Conclusion These findings suggest that fetal glucose consumption is balanced against the placental needs for glucose and that placental glucose consumption is a key modulator of maternal-fetal glucose transfer in women.