An Effect of Maternal Secondhand Smoke Exposure at Early Pregnancy on Autistic Behaviors at 5 Years of Age

Abstract

<Background>Autism Spectrum Disorders is a syndrome with multiple causes and different mechanisms leading to abnormal development. Only a few longitudinal studies have investigated the association between maternal SHS exposure and autistic behaviors. We examined the effect of Secondhand Smoke exposure on the autistic behaviors in children at 5 years to identify the sensitive time window of exposure considering potential gender difference.<Method>A total of 1,751 pregnant women and children participated in the prospective birth cohort study, Mothers and Children’s Health study since 2006. Information concerning SHS exposure was obtained from the children’s parents or guardians by means of a self-administered questionnaire that included a set of standardized questions commonly used in previous studies. A total of 458 children at 5 years were assessed for behavior by using the Social Responsiveness Scale (SRS). The association between SHS exposure at each time window and autistic behaviors was examined using generalized linear model adjusted for maternal age at pregnancy, maternal educational level, household income, household income, residential area, parity and early blood lead.<Results>SHS exposure at early pregnancy was significantly associated risk of autistic behaviors in boys while it was not at postnatal periods: for SHS in early pregnancy, score of Total - SRS increased by 2.66(95% CI 0.06, 5.26) in boys, in which the interaction effect of gender was significant (p-interaction: 0.01). However, the SHS exposure at any time did not show a significant association with autistic behaviors in girls.<Conclusion>SHS exposure on children’s autistic behavior at 5 years showed a susceptible exposure time window of early fetal period in boys. SHS exposure did not show an association with autistic behaviors in girls.