OBJECTIVE: To examine the relationship between maternal intelligence-mental health and neuropsychological development at age 14 months in a normal population, taking into account maternal occupational social class and education.
METHODS: We prospectively studied a population-based birth cohort, which forms part of the INMA (Environment and Childhood) Project. Cognitive and psychomotor development was assessed at 14 months using Bayley Scales of Infant Development. Maternal intelligence and mental health were assessed by the Cattell and Cattell test and the General Health Questionnaire-12 respectively.
RESULTS: We observed a crude association between maternal intelligence and cognitive development in children at 14 months but this association disappeared when maternal education was included. The associations were stratified by maternal education and occupational social class. Within the manual maternal occupational social class, there was a significant difference in cognitive development between children whose mothers scored in the highest tertile of maternal IQ and those whose mothers scored in the lowest tertile. In contrast, no differences were observed among children whose mothers were in the non-manual occupational social class.
CONCLUSIONS: The association between maternal intelligence and child cognitive development differed by occupational social class. While this association was not confounded by education or other variables in manual occupational social classes, maternal education explained this association among advantaged occupational social classes.
