Heavy drinking during pregnancy has long been known to affect a child's intelligence measures, but a new study published in the June 2006 issue of Alcoholism: Clinical & Experimental Research shows than even light-to-moderate drinking is associated with lower IQs in offspring at 10 years of age.
"The impact of heavy prenatal alcohol exposure on IQ ranges from a two- to a seven-point decrease," said Jennifer A. Willford, assistant professor of psychiatry at the University of Pittsburgh School of Medicine and lead author of the study. "IQ is a measure of the child's ability to learn and to survive in his or her environment.
"It predicts the potential for success in school and in everyday life. Although a small percentage of children are diagnosed with Fetal Alcohol Syndrome (FAS) each year, many more children are exposed to alcohol during pregnancy who experience deficits in growth and cognitive function."
"Intellectual functioning is a good first measure of the potential damaging effects of prenatal alcohol exposure," added Paul D. Connor, clinical director of the Fetal Alcohol and Drug Unit and assistant professor in the department of psychiatry and behavioral sciences at the University of Washington. "However, mental retardation only characterizes a minority of patients with FAS and Alcohol-Related Neurodevelopmental Disorder (ARND).
"There are a number of domains of cognitive functioning that can be impaired even in the face of a relatively normal IQ, including academic achievement (especially arithmetic), adaptive functioning, and executive functions (the ability to problem solve and learn from experiences).
"Deficits in intellectual, achievement, adaptive, and executive functioning could make it difficult to appropriately manage finances, function independently without assistance, and understand the consequences of – or react appropriately to – mistakes." The researchers analyzed data collected as part of the Maternal Health Practices and Child Development Project, a study of prenatal substance use among women in a prenatal clinic from 1983 to 1985. Women were assessed during each trimester of pregnancy, and again with their children at birth, eight and 18 months, and three, six and 10 years of age. At age 10, the children's cognitive ability was assessed using the Stanford Binet Intelligence Test.
Quit Drinking As Soon As Possible
"This study found that even light to moderate drinking during pregnancy can affect IQ," said Willford. "The effects of prenatal alcohol exposure on IQ were worse for children exposed to alcohol through the second trimester of pregnancy.""This latter finding," said Connor, "of greatest effects on intellectual functioning because of second-trimester drinking suggests that, with appropriate intervention procedures, even if alcohol was consumed early during pregnancy, cessation of drinking as soon as possible could have protective benefits on the developing fetus. This is one of the few longitudinal studies of prenatal alcohol exposure that specifically collected data on the timing of alcohol use and is a strength of the study."
Racial Differences Exist
"Our study also showed that prenatal alcohol exposure was associated with lower IQ for African-American but not Caucasian children, said Willford. "Importantly, we know that this racial difference was not due to differences in the amount or pattern of alcohol use during pregnancy or by differences in socioeconomic status. We cannot say why the racial difference exists, but laboratory animal and human studies show that it may be partly explained by genetic factors.""Similar findings have been described in other studies," concurred Connor, "however, it should not be construed that a child is protected from the damaging effects of prenatal alcohol exposure because of their ethnicity. Fetal Alcohol Spectrum Disorders can occur in any ethnic group."
Both Willford and Connor said that it remains unclear if there is a "safe" level of alcohol consumption during pregnancy.
No 'Safe' Level Determined
"We suggest that women speak with their obstetricians about drinking when they are planning a pregnancy or when they learn that they are pregnant. Many women know about fetal alcohol syndrome and the effects of heavy drinking. However, studies are showing that even light-to-moderate levels of drinking during pregnancy also can be harmful."Since none of the studies has suggested a 'safe' level of alcohol exposure during pregnancy, we can only say it's safer not to drink at all," said Dr. Willford.
Source: The study, "Moderate Prenatal Alcohol Exposure and Cognitive Status of Children at Age 10," was published in the June 2006 issue of Alcoholism: Clinical & Experimental Research.
