The Mediating Role of SES on the Relationship between Pregnancy History and Later Life Cognition

Abstract

Objective: The association of pregnancy with later life cognition is not well understood. Few studies address the potential confounding role of socioeconomic factors on this relationship. We examined whether pregnancy was associated with cognitive function in a large, population-based sample of post-menopausal women and the potential mediating effects of education level and federal income-to-poverty ratio (PIR) on this relationship. Methods: Participants were 1,016 post-menopausal women from the National Health and Nutrition Examination Survey (NHANES). We utilized data from two study waves between years 2011-2014. Cognitive functioning was evaluated by: Digit Symbol Substitution Test (DSST), Animal Fluency (AF), Consortium to Establish a Registry for Alzheimers Disease CERAD word learning task (CERAD-WL) and CERAD delayed recall (CERAD-DR). Lifetime education level and federal income-to-poverty ratio (PIR) were examined as mediating factors. Regression models were used to examine the relationship between number of term pregnancies and incomplete pregnancies and cognitive performance. Results: A greater number of term pregnancies was related to worse performance on the DSST (p < .001), CERAD-DR (p < .007), and AF (p < .03). Conversely, greater incomplete pregnancies related to better CERAD-DR performance (p < .03). Significant associations between term pregnancies and cognitive scores were mediated by PIR but not education level. Conclusions: Higher number of term pregnancies was associated with worse cognitive performance, whereas higher number of incomplete pregnancies was associated with better cognitive performance. Results indicate the necessity to consider SES factors when studying the relationship between pregnancy and cognition.