The study was carried out at the Family Centre at the Obstetric Department at H:S Hvidovre Hospital, Copenhagen, Denmark. The purpose was to explore the relationship between prenatal alcohol-exposure and attention impairment and other behavioural problems in children.
The first study was a case series of 55 moderately and heavily alcohol-exposed children. The children were assessed at 0, 3, 6, 9, 12, 18, 24, 30, 36, 48, 60, 72 months by clinical examinations, and developmental level was assessed (Griffith's developmental test) a sub-sample was assessed by a neuropsychological test (NEPSY). Data on other risk factors were registered.
The second study was a cohort study of a low-risk group of 1863 urban women who in 1993 during pregnancy filled in a questionnaire registering their alcohol consumption. In 2000 they received a questionnaire about the child's behaviour. The questionnaire was developed during the study and measured behavioural problems associated to heavy prenatal alcohol exposure and ADHD (response rate 85.5%).
The case series showed that 67% of the heavily exposed children (≥7 drinks/week) developed attention impairment (AI). Early predictors of AI were neonatal withdrawal syndrome, vulnerability at 6-12 months and neurological symptoms at one year of age. Very heavily exposed children (>20 drinks/week) had an impaired developmental level; significantly lower the longer the child had been exposed, and the impairment increased, as the children grew older.
The cohort study showed that alcohol related behavioural problems and ADHD symptoms were highly correlated (factor correlation 0.91). Using multivariate analysis we found that prenatal alcohol exposure at low-level (1-6 drinks a week) was connected to slight but not significant increase in behaviour problem score. Tobacco exposure was also insignificant. The results are compatible with at the most a modest effect of low-level alcohol consumption, RR: 1.47 of behavioural problems between 0 and 4 drinks/week.
Significant predictors of behavioural problems were early weaning, young maternal age, low social status, psychotropic medication prior to the pregnancy and the child's sex (boy).
A high level of prenatal alcohol exposure (>20 drinks/ week) is a probable cause of impaired mean-developmental level and a probable additional cause of attention impairment. The results indicate that reduction of alcohol consumption even in the late pregnancy benefits the child on a long-term basis. Prenatal alcohol exposure at low-level, less than a drink a day was connected to slight and not significant increase in behaviour problem score.