• By Kevin Mount
  • Posted on Friday 15th February, 2008

Better reasons for pointing an accusing finger

Just because two things occur together doesn’t mean that one caused the other. It’s the difference between correlation and causation – something the media get into trouble for confusing in their headline coverage of scares (Even moderate drinking could harm, for example) and cures (Alcohol cuts strokes in women).It’s common knowledge that mothers who drink a lot while pregnant are more likely to have children with behavior or attention problems than mothers who don’t. And physicians recommend that pregnant women abstain. But most of the research in this area actually only shows that drinking is associated with later problems, not that drinking is the cause. In other words, studies don’t rule out the possibility that pregnant women who drink also have other traits (some of which might be encoded in their genes) which are the actual causes of their children’s difficulties.To remedy this weakness among earlier studies, a team of US researchers, headed by Brian D'Onofrio of Indiana University, looked at information collected on 8,621 offspring of 4,912 American mothers as part of the National Longitudinal Survey of Youth and the Children. They investigated whether something about mothers who drank during pregnancy – their income or educational levels, for example – could account for problems that their children experienced. They also considered whether differences in their mothers’ intake of alcohol during different pregnancies was related to differences in their siblings’ behavior. Were that the case, the researchers would have evidence that it was the alcohol in the mothers’ systems, rather than their genetic make-up, that caused their children’ problems. The Indiana team found that drinking during pregnancy was related to children’s conduct problems, even after various characteristics of their mothers were factored in. And heavier drinking during pregnancy was related to more behavior problems in the children. However, attention problems did not seem to be the result of mothers’ drinking.So doctors’ advice to refrain from drinking while pregnant still seems like good advice. Doing so probably helps to reduce the likelihood of having a child with behavior problems. However, it seems that attention problems cannot be blamed on alcohol consumption during pregnancy.[See also the University of Indiana coverage: Prenatal exposure to alcohol and conduct problems: A clearer link]• Summary of “Causal Inferences Regarding Prenatal Alcohol Exposure and Childhood Externalizing Problems” by Brian D'Onofrio, Carol Van Hulle, Irwin Waldman, Joseph Rodgers, Paul Rathouz, and Benjamin Lahey in Archives of General Psychiatry, Volume 64, Issue 11, pp1296-1304, November 2007.

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