(HealthDayNews) -- One of the cardinal rules for expectant moms: don't drink. But a new study out of Denmark is throwing that maxim into doubt. It finds that 5-year-olds whose mothers drank low to moderate levels of alcohol (between one and eight drinks a week) during early pregnancy showed no ill effects. Alcohol consumption during pregnancy that exceeded the "moderate" threshold, however, was associated with a lower attention span among children in that age group.