Previous studies have associated maternal drinking during pregnancy with several problems in offspring, including conduct problems, criminal behaviour, attention and impulsivity problems and alcohol disorders.
However, new questions have been raised about the strength of the evidence, as some researchers have suggested that certain family processes or genetic risk factors could be linked to both maternal drinking and childhood problems.
Brian M. D'Onofrio, Ph.D., of Indiana University, Bloomington, and colleagues analysed data from 4,912 mothers who enrolled in a large national survey in 1979. Yearly through 1994 and then every other year through 2004, the women answered questions about their substance use during each of their pregnancies. Beginning in 1986, 8,621 of their offspring were also assessed every other year between ages 4 and 11 for behavioural problems.
It was found that for each additional day per week, mothers who drank alcohol during pregnancy, their kids had an increase in conduct problems. This association remained even after factoring in other variables such as the mothers' drug use during pregnancy, education level or intellectual ability.
Children whose mothers drank alcohol during pregnancy also had more attention and impulsivity problems than unrelated children whose mothers did not drink. However, siblings whose mother drank more frequently during one pregnancy had the same level of difficulty with attention and impulsivity.
"These results are consistent with prenatal alcohol exposure exerting an environmentally mediated causal effect on childhood conduct problems, but the relation between prenatal alcohol exposure and attention and impulsivity problems is more likely to be caused by other factors correlated with maternal drinking during pregnancy," the authors said.
These other factors may include the use of tobacco, illegal drugs and other substances in addition to alcohol. "The findings thus support a strong inference that prenatal alcohol exposure causes an increased risk of offspring conduct problems through environmental processes," the authors said.
"Therefore, prevention efforts should continue to target alcohol consumption during pregnancy," they added.