Many children adversely affected by maternal drinking during pregnancy cannot be identified early in life using current diagnostic criteria for fetal alcohol spectrum disorder (FASD). In the current study, conducted with pregnant rats, researchers examined whether ethanol-induced alterations in placental gene expression may be useful as diagnostic indicators of maternal drinking during pregnancy and as a prognostic indicators of risk for adverse neurobehavioral outcomes in affected offspring. Analyses of more than 28,000 genes revealed that the expression of 304 known genes was altered twofold or greater in placenta from ethanol-consuming pregnant rats compared with controls. Gene expression changes involved proteins associated with central nervous system development; immunological responses; endocrine function; skeletal, cardiovascular, and cartilage development, as well as other effects. These results suggest that the expression of a sufficiently large number of placental genes is altered after moderate drinking during pregnancy to warrant more detailed investigation of the placenta as a biomarker system for maternal drinking during pregnancy and as an early indicator of FASD. Given the accessibility of placentas following child birth, the gene changes identified in this study have the potential to serve as practical biomarkers of prenatal alcohol exposure and/or predictors of FASD in offspring. In addition, the identity of these genes could inform our understanding of alcohol's effects on placental function.