Authors' response to: Different perspectives on the methodology of studying the potential effects of different alcohol drinking patterns in early pregnancy on the neuropsychological development of young children

Abstract

for their interest in our recently published five papers on the potential effects of low to moderate alcohol intake during pregnancy. These papers also looked at the potential effects of alcohol binge drinking in early pregnancy on the neuropsychological development in young children.First, we agree that the null results from our studies must be interpreted with caution. The published results were limited to the measurement of three neuropsychological effects in children aged 5 years, and did not include other ages or other health outcomes. Although these studies suggest that there are no serious effects on these three functions with low to moderate levels of alcohol consumption, they cannot rule out other harmful effects or negative health outcomes in older children.We agree that reliable measurement of alcohol consumption, particularly alcohol consumption by pregnant women, is very difficult in both clinical and research settings. It is generally acknowledged that pregnant women are likely to underreport their alcohol consumption, irrespective of the actual level of consumption. This problem has been assessed extensively in the literature and many improvements in questions and the manner of questioning have been developed that have increased the reliability of the information. These improved techniques were applied in the Danish National Birth Cohort (DNBC), and some relevant references are provided in the papers. Based on post-partum meconium analysis, Garcia-Algar et al.2 suggest that pregnant women do not underreport, but misreport, and therefore that self-reports are unreliable and that no conclusion can be drawn. Although self-reporting may be flawed, we believe that it still yields important and useful information. At the time of data collection on alcohol exposure through the DNBC, procedures for obtaining exposure information represented a significant step forward. Questions were asked during pregnancy rather than years later after a child was found to have problems. We agree that, as bio-measures may be developed and refined, future studies may be able to hone in on more precise aspects of exposure.Interestingly, in their own recent paper, 5 the authors state that, 'mothers from Mediterranean countries tend to underreport their drinking…., probably due to social pressure and guilt feeling.' This may be correct, and stresses the importance of underreporting. This may also explain why Astley and Grant, 4 describe that a small proportion of mothers with children who have fetal alcohol syndrome (FAS) reported a low to moderate weekly intake of alcohol. To our knowledge, in the scientific literature, FAS is generally described for much higher levels of prenatal exposure. As mentioned in our papers, one of the important methodological aspects of the collection of exposure data relates to the fact that, in Denmark, many pregnant women, doctors and midwives consider low to moderate alcohol consumption (such as the levels investigated in this study) to be acceptable.6-8 Therefore, as opposed to many other coun...

Prenatal Alcohol Exposure and Child Psychosocial Behavior: A Sibling Fixed-Effects Analysis

“…Although it is widely accepted that binge drinking during pregnancy increases the risk of fetal alcohol syndrome ( 10 , 11 ), whether low-to-moderate levels of alcohol consumption during pregnancy can affect children's health remains controversial ( 12 – 14 ). A recent meta-analysis which assessed both normal and abnormal development as continuous variables concluded that mild-to-moderate prenatal alcohol exposure (PAE) during all trimesters was not associated with child psychosocial outcomes such as cognition and mental development ( 12 ).…”

“…There are several reasons why it is challenging to investigate the effects of PAE on children's behavioral problems. First, mothers tend to under report their drinking levels during pregnancy because of prevailing social norms ( 14 ). Second, any correlation between maternal drinking during pregnancy and child outcomes is likely to be confounded by a range of unobserved factors including family environment and shared genetic influences.…”

Review shows that early foetal alcohol exposure may cause adverse effects even when the mother consumes low levels

“…After five Danish studies were published in 2012, the media came to the conclusion that light‐to‐moderate drinking during pregnancy did not harm the foetus, which may makes public health warnings about being careful confusing for women . Contrary to the media reports, the authors of the original Danish studies were actually cautious and advised women not to drink alcohol during pregnancy . A later meta‐analysis found even if a woman did not drink daily, her alcohol consumption could still be detrimentally associated with her child's behaviour problems .…”