Low-level alcohol consumption in early pregnancy may not affect child intelligence, attention or executive function at 5 years of age
Question: How do different alcohol drinking patterns in early to mid pregnancy affect the child's intelligence, attention and executive function?
Population: 1628 women, drawn originally from the Danish National Birth Cohort, recruited at their first antenatal visit to a general practitioner.
Setting: Denmark; 1997–2008.
Prognostic factors: Average alcohol intake during early to mid pregnancy (median 17 weeks of gestation, range 7–39 weeks), categorised into four groups by number of standard drinks (containing 12 g of pure alcohol) consumed per week: (1) zero; (2) 1–4; (3) 5–8 and (4) 9 or more. In addition, frequency and timing of binge drinking (5 or more drinks on a single occasion) were recorded. Women were divided into ‘any binge drinking’ (1 or more episodes) and ‘no binge drinking’ categories. Potential confounding factors were adjusted for in the analyses.
Outcomes: Offspring intelligence, attention and executive function at age 5 years. Intelligence was assessed using the shortened forms of the Wechsler Primary and Preschool Scales of Intelligence—Revised (WPPSI-R). Attention (selective attention and sustained attention) was measured with the Test of Everyday Attention for Children at Five (TEACh-5). Executive function was measured using an 86-item questionnaire, the Behaviour Rating Inventory of Executive Functions (BRIEF) and Global Executive Composite (GEC) score which were either completed by the mother or staff at day-care facilities.
Almost half of the women (46.6%) did not drink in early to mid pregnancy, with 41.5% drinking an average of 1–4 drinks per week (median 1 drink), 10.7% drinking 5–8 drinks per week (median 5 drinks) and 1.2% drinking 9 or more drinks per week (median 10 drinks). Only under a third (30.4%) reported no binge drinking in early to mid pregnancy, while about 48% reported one episode of binge drinking and the remainder (about 22%) reported between 2 and 12 episodes. Unadjusted analyses found no significant association between average alcohol consumption (p=0.63) and binge drinking (p=0.28) in early to mid-pregnancy and child's neurodevelopmental outcomes at age five. Adjusted analyses also found no significant association between average alcohol consumption (p=0.74) and binge drinking (p=0.96) in early to mid-pregnancy and child's outcomes. Similarly, no statistically significant effects were shown for the three neurodevelopmental outcomes when assessed individually.
There was no significant association between low-to-moderate average alcohol consumption or binge drinking in early-to-mid pregnancy and neurodevelopment of children at the age of 5 years.
Correspondence to: Dr US Kesmodel, Department of Public Health, Section of Epidemiology, Aarhus University, Bartholins Allé 2, 8000 Aarhus C, Denmark; email@example.com
Sources of funding: The Centers for Disease Control and Prevention (CDC), the Danish National Board of Health, the Lundbeck Foundation, Ludvig & Sara Elsaas’ Foundation, the Augustinus Foundation and Aase & Ejnar Danielsen's Foundation.
- Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, Detroit, Michigan, USA Correspondence to: Dr Joseph L Jacobson, Department of Psychiatry and Behavioral Neurosciences, Wayne State University School of Medicine, 2751 E. Jefferson, Suite 460, Detroit, Michigan 48207, USA;
Kesmodel and colleagues have published new analyses focusing on the effects of low-to-moderate prenatal alcohol exposure on child cognition. One important limitation of this population-based study is the failure to consider the consistent body of evidence linking moderate drinking (defined as 7–13 drinks/week) to poorer growth and cognition.1 ,2
No significant effects were found on 5-year cognition, but assessments at school age, particularly of executive function, are more valid and other specific domains are often more sensitive. Although moderate (and higher) levels of exposure were oversampled, a major weakness of the study was poor sensitivity to evaluate the effects of moderate drinking. The 0 or 1–4 (median=1 drink/week) group consisted of 933 participants, 175 were light drinkers (5–8/week; median=5), and only 20 clearly fell in the moderate range group (>9/week; median=10). It is noteworthy that, although not significant, cognitive performance was markedly poorer in the moderate group.
Exposure was measured by only a single report obtained at 7–39 weeks gestation. Given that the effects can vary considerably depending on the timing of exposure, and as drinking levels may fluctuate across pregnancy, this limitation further reduced sensitivity to teratogenic effects. Previous studies reporting effects from moderate exposure measured exposure repeatedly at consistent time points during pregnancy. This study also failed to consider moderator variables, particularly maternal age and alcohol abuse/dependence, that increase the risk of effects from moderate exposure.3
Binge drinking was also rare in this sample. Since 69% of those who binged did so only once, ‘any’ versus ‘no’ binge drinking were compared, precluding assessment of the frequency of binge drinking at which effects might become evident.
Despite their negative findings, the authors advise abstention from alcohol during pregnancy. We are concerned, however, that this report of an absence of effects, despite inadequate power to examine the consequences of moderate daily and occasional binge drinking, may lead to reduced vigilance by clinicians in urging pregnant women to abstain during pregnancy.