Article Title: Associations between maternal infections during pregnancy and childhood IQ scores using the ALSPAC birth cohort Running title: Maternal Infections During Pregnancy and Childhood IQ Authors:

Maternal prenatal infections have been linked to children’s neurodevelopment and cognitive outcomes. It remains unclear, however, whether infections occurring during specific vulnerable gestational periods can affect children’s cognitive outcomes. The study aimed to examine maternal infections in each trimester of pregnancy and associations with children’s verbal, performance, and total IQ scores. The ALSPAC birth cohort was used to investigate associations between maternal infections in pregnancy and childhood IQ outcomes. Infection data from mothers and cognition data from children were included with the final study sample size comprising 7,410 mother-child participants. Regression analysis was used to examine links between maternal infections occurring at each trimester of pregnancy and children’s cognitive IQ scores at 18 months, 4 years, and 8 years. Infections in the third trimester were significantly associated with decreased verbal IQ at age 4 (p<.05, adjusted R = .004); decreased verbal IQ (p<.01, adjusted R = .001), performance IQ (p<.01, adjusted R = .0008), and total IQ at age 8 (p<.01, adjusted R = .001). Results suggest that later maternal infections could have a latent effect on cognitive development, only emerging when cognitive load increases over time, though magnitude of effect appears to be small. Performance IQ may be more vulnerable to trimester-specific exposure to maternal infection as compared to verbal IQ. Future research could include examining potential mediating mechanisms on childhood cognition, such as possible moderating effects of early childhood environmental factors, and if effects persist in future cognitive outcomes.