Objective. We aimed to replicate a previous study of 1-year-olds that reported a deficit in motor development associated with moderate alcohol use during lactation, using a different but comparable population.
Methodology. The mental development of 915 18-month-old toddlers from a random sample of a longitudinal population-based study in the United Kingdom was measured using the Griffiths Developmental Scales. Frequent self-administered questionnaires during and after pregnancy provided maternal data. The dose of alcohol available to the lactating infant was obtained by multiplying the alcohol intake of the mother by the proportion of breast milk in the infant’s diet. We compared this dose with the Griffiths Scales of Mental Development, taking into account potentially confounding variables.
Result. Three of the Griffiths scales increased slightly but significantly with increasing infant alcohol exposure; there was no association in the remaining 2 or average of the scales.
Discussion. We were unable to replicate the earlier deficit in motor skills associated with lactation alcohol use. One reason may be that the dose of alcohol reaching the lactating infant is small, and tests of infants and toddlers have limited ability to pick up small effects. Studies of older children may resolve the question of the safety of drinking while nursing.