Placental nutrient transport assessment is essential in experimental models to provide a functional measure of fetal nutrient supply and uptake and their responses to interventions. In small animals including mouse, radiolabelled tracers have been used to measure passive and active transport of solutes across the placenta, which is reduced in IUGR (1,2). Use of fluorescent rather than radioactive labels for solutes has benefits for safety and waste disposal. In pilot studies, we demonstrated transfer of fluorescently-labelled 2-deoxyglucose (IRDye800CW 2-DG, LI-COR Biosciences, Lincoln, NE) across the placenta into fetal circulation in anaesthetised late pregnant mice. When injected into conscious mice, transfer from placenta to fetus stabilised by 30 minutes after injection and similar levels were maintained for 120 minutes. Our next aim was to test whether dye transport differed between littermates with the lowest (low PE) and highest (high PE) placental efficiency for their litter, defined as fetal:placental weight ratio. Fluorescently-labelled 2-DG was injected into the tail vein of pregnant CBAF1 mice 2 or 24 h before tissue collection at 17.5 or 18.5 d gestation. Fluorescent signals were measured (800 nm channel, Odyssey Imaging System, LI-COR) in homogenised tissues of low PE and high PE littermates. Fetal uptake of fluorescently-labelled 2-DG across the placenta was calculated as total fetal fluorescence per gram of placenta. Littermates were compared using paired t-test. Fetal 2-DG uptake was higher in high PE than low PE littermates of dams injected either 2 h (P=0.032, n=3 litters) or 24 h (P=0.020, n=6 litters) before tissue collection. This method is therefore able to differentiate littermates that differ in placental function in the late pregnant mouse. We are currently performing additional studies investigating the relationship between fetal 2-DG uptake and Doppler indices of fetal blood supply, and effects of IUGR on fetal 2-DG uptake in late gestation.