Maternal mental health and offspring's IQ: Evidence from two Brazilian birth cohorts

Maternal mental health during different stages of life can have a significant impact on a child's cognitive development. This study aimed to investigate the association between maternal CMD at two distinct stages of the offspring's life (at 3 months and 11 years) and their IQ scores at 6 and 18 years across two birth cohorts. The study utilized data from two Brazilian birth cohorts: the 1993 cohort (full sample: N = 3719, subsample: N = 436), and the 2004 Pelotas Birth Cohort (N = 3440). IQ assessments were conducted at ages 18 and 6, employing the Wechsler Adult Intelligence Scale, third version (WAIS-III), and Wechsler Intelligence Scale for Children, third version (WISC-III), respectively. The presence of maternal CMD at 3 months and 11 years of age was evaluated using the Brazilian version of the Self-Reporting Questionnaire (SRQ-20). After adjustment, participants whose mothers experienced CMD at 3 months had average IQ scores 1.74 (95 % CI: −2.83 to −0.67) and 2.79 (95 % CI: −5.54 to −0.04) points lower at ages 6 (2004 cohort) and 18 (1993 cohort subsample), respectively. Furthermore, in the 1993 cohort (both full and subsample), maternal CMD at 11 years was associated with lower IQ scores at age 18. Understanding the mechanisms underlying this association, emphasized by these findings, is crucial for promoting children's cognitive development, educational achievement, and overall well-being. •An association was observed between maternal common mental disorders (CMD) and the children's IQ scores.•Offspring of mothers with CMD at 3 months had lower IQ scores at ages 6 and 18.•Offspring of mothers with CMD at 11 years had lower mean IQ at 18 than those whose mothers did not have CMD.