Infant temperament, maternal mental state and child behaviour problems.

In a longitudinal study of firstborn children, interview-based measures of temperament were obtained when the infants were aged four months. From the individual items an 'easy-difficult' scale was constructed. The scale showed a fair internal consistency and reasonable test/retest reliability, and the obtained scores appeared to be independent of previous and current maternal attitudes and mental state. A wide range of scores was obtained. Four-month temperament, as reflected on this scale, related to the presence of behavioural problems when the children were aged 42 months, with 'difficult' children developing higher rates of problems. Problems at 42 months also related strongly to the mother's mental state at the time, with the children of depressed mothers showing more problems. When all three items--four-month temperament, 42-month behavioural problems and 42-month maternal depression-were examined, a strong interaction effect was found. Maternal depression was associated with behavioural problems only if the child had been in the extreme quartiles on the temperament measure. Some evidence suggested that an infant's temperament could affect its mother's later mental state.