Heavy drinking during pregnancy can cause birth defects and other alcohol-related effects. Because costs associated with fetal complications are high, health care organizations are invested in finding ways to intervene with pregnant drinkers. We describe a computerized intervention tested at prenatal clinics that uses drink size as a way of creating dialogue about pregnancy drinking. The intervention helps pregnant women screened as at-risk for alcohol use recognize how much they actually drink, using calibrated glassware and beverage containers along with computer graphics designed to define true volume for specific alcoholic beverage types. The intervention promotes abstinence; however, if that is not an obtainable goal, women are taught ways to cut down as much as possible during the rest of their pregnancy. Clinician feedback has been very positive, and the few women who continued to drink did not drink frequently or engage in binge drinking. Further, their average daily volume was 1 drink per day.