November 15, 2012
Moderate Drinking During Pregnancy Affects Childs IQ
Connie K. Ho for redOrbit.com — Your Universe Online
In the research project, the scientists studied more than 4,000 mothers and their children. These subjects were part of the children of the 90s study (ALSPAC). The study was considered the first of its kind, as past studies have focused on observational evidence rather than genetic evidence. It evaluated the female participants with Mendelian randomization, a new technique that can study the connections between exposures and the development of diseases with genetic variants.
“This is a complex study but the message is simple: even moderate amounts of alcohol during pregnancy can have an effect on future child intelligence. So women have good reason to choose to avoid alcohol when pregnant,” said Ron Gray, a researcher from the University of Oxford, in the statement.
In conducting the study, the researchers had the mothers conduct questionnaires on the alcohol intake when they were 18 weeks pregnant. The questionnaire included topics such as average amount of alcohol consumed and frequency of alcohol consumption before the pregnancy, during the first trimester, and when they felt the baby first moved or two weeks after feeling the baby first move. At the 32-week pregnancy period, the mother was given another questionnaire to fill out regarding average weekday and weekend alcohol consumption. Females who noted that they drank less than one per week in the first trimester or during the baby´s first movement were considered to have drank during their pregnancy. Then at the 18 weeks and 32 weeks period, they were also requested to report on the number of days in the past month they had drank two pints of beer or the equivalent amount of alcohol. Those who completed this action were labeled as a “binge drinker.” When the child participants were eight years old, they completed an IQ test.
Based on the findings, the team of investigators discovered that there were four genetic variations related to alcohol-metabolizing genes and low IQ levels for the 4,167 children. For children who were exposed to small traces of alcohol, they were shown to have an average of almost two points less based on the genetic modification they expressed. This change was only seen with the children of mothers who drank moderate amounts during their pregnancy, leading researchers to believe that the genetic modification was due to the alcohol exposure.
Scientists described how, when an individual drinks, a group of enzymes will change the ethanol to acetaldehyde. Genes that have different variations could have a less effective way in metabolizing ethanol, which causes alcohol levels to be higher and persist for a longer period of time. Researchers believe that, the faster ethanol can be metabolized, the less probable that the brain will develop abnormally because the fetus has less exposure to alcohol.
“Our results suggest that even at levels of alcohol consumption which are normally considered to be harmless, we can detect differences in childhood IQ, which are dependent on the ability of the fetus to clear this alcohol. This is evidence that even at these moderate levels, alcohol is influencing fetal brain development,” said Sarah Lewis, the study´s main author and a member of the University of Bristol, in a prepared statement.
The researchers say their findings can help clear up contradictory guidelines on alcohol consumption during pregnancy. Some guidelines previously stated the need to completely abstain of alcohol, while others stated that moderate use is safe during pregnancy. Furthermore, other studies in the past have shown conflicting and inconsistent results on the impact of small levels of exposure of alcohol for a child´s IQ level. Researchers believe that other lifestyle and social factors like diet, smoking, a mother´s age and education, made it difficult to isolate the results that were based solely on alcohol consumption.
The findings were recently published in PLOS ONE.