Danish study raises further questions regarding alcohol and pregnancyJanuary 05, 2014
Basis for these rather controversial headlines is coming from a study by University of Copenhagen PhD student Janni Niclasen and media uses the opportunity to open a long-running debate over whether it is safe for pregnant women to drink.
These articles are focusing on the finding that women who drank in moderation during pregnancy seem to have children who are behaving better compared to women who abstained. Janni Niclasen explained to NordAN that for her the main finding was coming from the “ background characteristics” of these different groups and what was the role of different confounding factors.
“In all of the studies included in my Ph.D. I looked at seven year old children. I looked at behavioural and emotional development at age seven,” Janni Niclasen explained. “In the first study that I carried out I looked at prenatal exposure to alcohol and emotional and behavioural development at age seven. In this study I found the most favourable outcomes for the children of the mothers who drank 90+ units of alcohol in full pregnancy (the high exposed group in this study) and I found the least favourable outcomes for the children of the abstaining mothers. Because I thought that this was really surprising and that it made no sense from a theoretical perspective I thought that it would be useful to approach and understand the findings from a different perspective.”
“I therefore decided to investigate the background characteristics of the abstainers and the high intakers (90+ units in pregnancy) in much detail in order to see if such factors could explain the findings. And in this study I really did find tremendous differences between the exposure groups. The abstainers were the poorest educated, they were least likely to do exercises and eat healthy foods, but were the most likely to smoke, have a BMI (body mass index) outside of the normal range, watch television etc. The opposite pattern was true for the high intakers (90+ units in alcohol). Further, (and maybe because I am a psychologist) I am speculating that these very big differences that I observed between the groups on the socio-economic and lifestyle factors also will be present between the groups on psychological, childhood-related factors. This is interesting because we know that these factors really has a huge impact on cognitive and mental development. Unfortunately we do not have such data in the large-scale birth cohorts. But my point is that these factors play a crucial part in the results we see in the observational studies and that the results probably reflect these factors rather than the biological influence of alcohol per se.” Niclasen told.
The role of these differences was highlighted also when we asked dr Diane Black, the chairperson of the European FASD Alliance to comment this study.
“People who do not drink at all tend to be poorer, less-educated, younger, sick or with a less healthy lifestyle; people who drink moderately are highly educated, with a better income and a healthy diet, they exercise, they have good health-care; and on the extreme end, people who drink really a lot are probably very unhealthy and addicted. So all these studies show that moderate drinkers have healthier children/less cancer/less heart disease/etc. This is the “healthy lifestyle” effect,” Diane Black told.
“The growing opinion (articles by O’Leary and Janni Niclasen herself) is that due to all the confounders, human studies do not show what is claimed they show. Zuccolo et al shows that if you can separate the socioeconomic strata into those who drink more and those who drink less, the children of mothers who drank less in fact do slightly better on certain measures. These researchers used data from the ALSPAC study, and separated the groups based on a gene which does not affect socioeconomic level or education level, but does affect level of drinking. Not surprisingly, this study did not hit the press, as it shows what people do not want to see—that given the same socioeconomic level and lifestyle, it is all the same better not drink during pregnancy
Finally, of course, human studies give confusing results due to all the possible confounding factors. Thus animal studies or increasingly, simply cell culture studies, are best to study low level effects of alcohol, as all conditions can be controlled and compared. Studies by Idrus and by Olney (just as examples, there are many more) show that even a single moderate exposure is enough to kill brain cells in the developing fetus,” dr Black explained.
Media seems to put major focus on studies that make any positive claims for moderate alcohol use. As vast majority of people drink in western world, there seems to be a logical interest in findings somekind of proof or justification that this habit is not only for bad.
“I greatly believe that the findings from studies which find moderate amounts of alcohol to be protective for the developing foetus, probably reflect unmeasured and residual confounding factors (i.e. socioeconomic, lifestyle and childhood related psychological factors that are not sufficiently taken into consideration in the statistical analyses),” responds Niclasen. “In Denmark we see that the most well-educated are drinking. These are the women that does everything else right for their children – they feed them organic food, they breastfeed, give them organic clothes etc. But, interestingly, when it comes to giving up their Saturday night glass of red wine they are not willing to do this. I think that they think that ‘I did all right, and so will my child’. At least in Denmark it is not a particular popular think to recommend abstinence…”
by Lauri Beekmann