Context

Two large population-based studies have recently reported no adverse effects of prenatal alcohol exposure at low-to-moderate levels on child academic underachievement and behaviour. However, these negative findings are inconsistent with research from prior longitudinal cohort studies that have detected effects of moderate alcohol exposure on growth, cognition and behaviour,1 ,2 using prospective ascertainment of maternal alcohol use3 and consideration of appropriate effect modifiers,4^–6 while controlling for potential confounders, including smoking and drug use, sociodemographic factors and maternal IQ. A careful review of these two recent studies illustrates the methodological challenges associated with detection of the effects of low-to-moderate levels of prenatal alcohol consumption.