Commentary on Day and Colleagues (2013): The Association Between Prenatal Alcohol Exposure and Behavior at 22 Years of Age—Adverse Effects of Risky Patterns of Drinking Among Low to Moderate Alcohol-Using Pregnant Women

Day and colleagues have presented the first data showing that the behavioral effects of low to moderate prenatal alcohol exposure seen in childhood and adolescence persist into adulthood. Using the Achenbach Adult Self-Report, they found dose-dependent effects of prenatal exposure on internalizing, externalizing, and attention problems that persist in young adults and, thus, appear to be permanent. To date, few studies have attempted to identify thresholds atwhich prenatal alcohol exposure is harmful, although the animal literature suggests that even 1 to 2 binge episodes can result in adverse effects in the offspring. Four prospective longitudinal studies have reported adverse effects at what can be characterized asmoderate exposure levels based on NIAAA criteria, but moderate drinking women often concentrate their alcohol use on 1 to 2 days perweek, thereby engaging in binge drinking. In this study, binge drinkingwas not a strong predictor of adverse outcome when average daily dose was held constant, a conclusion that the authors note runs “counter to studies that have reported that binge drinkinghas a greater effect.” This inconsistencymaybedue to the difficultyof allocating variance that is shared (overlapping) betweenaverage daily dose and binge drinking (i.e., dose/occasion). Data from laboratory animal studies, in which dosage can be manipulated experimentally, demonstrate that a higher dose per occasion, the key feature of binge drinking, leads to more severe adverse effects. Day and colleagues’ findings of adverse effects at low levels of exposure provides clear evidence that there is no safe level of drinking during pregnancy and that, even at low levels, drinking results in irreversible behavioral impairment. On the other hand, given the evidence from the animal and most human studies, it is important for all women who drink during pregnancy, even at light to moderate levels, to recognize that minimizing their intake per occasion and refraining frombingedrinking can reduce risk to the fetus.