The learning and memory disabilities associated with fetal alcohol spectrum disorder (FASD) are due, in part, to hippocampal damage caused by ethanol exposure during prenatal development. However, the mechanism by which alcohol damages the developing hippocampus remains poorly understood. In the current study, researchers examined how ethanol exposure in neonatal rats – a period that is developmentally equivalent to the third trimester of pregnancy in humans -- affects neuronal activities in the hippocampus. They report that in vivo and in vitro ethanol exposure potently inhibits molecular processes that are vital for the proper function and maturation of hippocampal neurons. Most importantly, the ethanol effect reaches significance at concentrations that can be achieved by a pregnant woman consuming less than a single standard drink in an hour. Although many other studies have shown effects of ethanol on synaptic function in developing neurons, the study reported here reveals the most potent effect of ethanol to date. It suggests that even low amounts of alcohol consumption during pregnancy may cause irreversible effects on hippocampal neurons and contribute to FASD.