摘要Pregnant women are often complicated with diseases that require treatment with medication.Most drugs administered to pregnant women are off-label without the necessary dose,efficacy,and safety informa-tion.Knowledge concerning drug transfer across the placental barrier is essential for understanding fetal drug exposure and hence drug safety and efficacy to the fetus.Transporters expressed in the placenta,including adeno-sine triphosphate(ATP)-binding cassette efflux trans-porters and solute carrier uptake transporters,play important roles in determining drug transfer across the placental barrier,leading to fetal exposure to the drugs.In this review,we provide an update on placental drug transport,including in vitro cell/tissue,ex vivo human placenta perfusion,and in vivo animal studies that can be used to determine the expression and function of drug transporters in the placenta as well as placental drug transfer and fetal drug exposure.We also describe how the knowledge of placental drug transfer through passive diffu-sion or active transport can be combined with physiologically based pharmacokinetic modeling and simulation to predict systemic fetal drug exposure.Finally,we highlight knowl-edge gaps in studying placental drug transport and predict-ing fetal drug exposure and discuss future research directions to fill these gaps.