Nowadays, mother-to-child HIV transmission is the main cause of paediatric HIV infections. Yet, this way of transmission is effectively limited by the use of antiretroviral therapies during pregnancy in HIV infected women. The study TEmAA (ANRS 12109) we conducted allowed us to suggest a therapeutic scheme of administration of the association tenofovir disoproxil fumarate (TDF) - emtricitabine (FTC) to reduce the risk of postpartum resistance that may occur with the administration of a single dose of nevirapine before delivery. However, we also observed a large interindividual variability of TDF in vivo placental transfer that remained unexplained. Placental membrane transporters, including efflux transporters belonging the ABC transporter superfamily and uptake transporters, may constitute a source of variability. In this case, we showed such an association for maraviroc with a significant inverse correlation between its clearance index and the placental expression level of several efflux transporters of the ABCC/MRP family. Regarding TDF, it has been shown that this drug is a substrate of several efflux transporters (ABCC2/MRP2, ABCC4/MRP4, ABCC10/MRP7) and an uptake transporter (hOAT3). As these transporters are expressed on the placental barrier, it may be hypothesized that their expression levels could contribute to modulate the placental transfer of this drug. To test this hypothesis, an ex vivo model known as "the perfused ex vivo cotyledon model" allows to reproduce the conditions of the third trimester of pregnancy. Our first aim is to evaluate the potential effect of ABCC2, ABCC4, ABCC10 and hOAT3 placental expression on TDF placental transfer (First year). We also want to investigate whether a potential interaction between TDF and FTC could take part to variability.