Does Light Drinking during Pregnancy Relate to Behavioral or Cognitive Problems in the Child?

Data from the first 2 sweeps of the nationally representative UK Millennium Cohort Study, a longitudinal birth cohort study begun in 2001, were used to relate drinking patterns during pregnancy with behavioral and cognitive outcomes in children at 3 years of age (n=12,495). Behavioral problems were indicated by scores above defined clinically relevant cutoffs on the parent-report version of the Strengths and Difficulties Questionnaire (SDQ). Cognitive ability was assessed using the Naming Vocabulary subscale from the British Ability Scale (BAS) and the Bracken School Readiness Assessment (BSRA).

• There was a J-shaped relationship between maternal drinking during pregnancy and the likelihood of scoring above the cutoff on the Total Difficulties Scale and the Conduct Problems, Hyperactivity, and Emotional Symptom subscales of the SDQ. Children born to light drinkers were less likely to score above the cutoff than children of abstinent mothers, while those born to heavy drinkers were more likely to score above the cutoff.

• Boys born to mothers who had up to 1–2 drinks per week or per occasion were less likely to have conduct problems (odds ratio [OR], 0.59) or hyperactivity (OR, 0.71). These effects remained in fully adjusted models. Girls were less likely to have emotional symptoms (OR, 0.72) or peer problems (OR, 0.68) compared with those born to abstainers. These effects were attenuated in fully adjusted models.

• Boys born to light drinkers had higher cognitive-ability test scores compared with boys born to abstainers. The difference for the BAS was attenuated after adjusting for socioeconomic factors, while the difference for the BSRA remained statistically significant.

Comments:

There were marked socioeconomic differences associated with women’s drinking in this study (e.g., both abstainers and heavy drinkers tended to have lower education and social status and smoked more than light drinkers). Many of the purported “beneficial” effects of light drinking were not statistically significant when these factors were taken into consideration. Hence, I agree with the authors that social circumstances, rather than the direct impact of ethanol, may be responsible for the relatively low rates of behavioral difficulties and cognitive advantages in children whose mothers were light drinkers. Nevertheless, this analysis of data collected in children at 3 years of age does not support a number of studies and governmental guidelines saying that even very light drinking during pregnancy leads to later behavioral and cognitive problems in the child. R. Curtis Ellison, MD

Reference:

Kelly Y, Sacker A, Gray R, et al. Light drinking in pregnancy, a risk for behavioural problems and cognitive deficits at 3 years of age? Int J Epidemiol. 2009 Feb;38(1): 129–140.