A study of 84 twin/sibling pairs exposed to alcohol in utero shows that two fetuses exposed to identical levels of alcohol can experience strikingly different levels of neurological damage. Risk of damage does not depend solely on the pregnant woman’s alcohol consumption; rather, fetal genetics plays a vital role, according to findings published today in the journal Advances in Pediatric Research.
“The evidence is conclusive,” said lead author Susan Astley Hemingway, professor of pediatrics at the University of Washington School of Medicine.
From a public-health standpoint, she said, the biggest take-away is that a fetus’ genetic makeup is a determinant to the risk of neurological damage from a mother’s alcohol consumption. To protect all fetuses, including those most genetically vulnerable, the only safe amount of alcohol is none at all, the report concludes.
In the study, UW Medicine researchers with the Fetal Alcohol Syndrome Diagnostic & Prevention Network analyzed data that had been gathered over more than 26 years. They found that when twins with identical DNA experienced identical alcohol exposure, the fetal alcohol outcomes were identical. In contrast, among genetically non-identical twin pairs with identical alcohol exposures, their fetal alcohol outcomes often differed, sometimes strikingly: one could be born with severe fetal alcohol syndrome (FAS) and the other only mildly affected.
This study, the largest of its kind, comes as some clinicians and researchers continue to advocate that light drinking, generally defined as one alcoholic drink per day, is OK for pregnant women. Astley Hemingway has argued against that point of view for years. Even one drink a day can place some fetuses at significant risk, she wrote in an opinion-editorial last fall. One of every 14 children diagnosed with fetal alcohol syndrome at UW Medicine had a reported exposure of one drink per day.
