Grandparent Prenatal Tobacco, Alcohol, Coffee, and Tea Consumption and Autism in the Third Generation

ABSTRACT Exogenous prenatal exposures may affect neurodevelopment across multiple generations. We investigated grandmother and grandfather smoking, alcohol, coffee, and tea consumption during pregnancy in relation to their grandchildren's risk of autism spectrum disorder (ASD). Pregnant participants (grandparent generation) in the Child Health and Development Studies (CHDS) were interviewed between 1959 and 1967 about their own and their partners' smoking and consumption of alcohol, coffee, and tea. CHDS participant records were linked to 18,053 third‐generation California births from 1989 to 2014, from which ASD cases were identified from Department of Developmental Services records. We estimated adjusted relative risk (aRR) of ASD associated with grandparents' smoking and consumption of alcoholic beverages, coffee, and tea from log‐binomial regression models adjusted for grandparents' age, education, and grandmother's race. Grandfather's overall tobacco smoking (including pipes and cigars) during their partner's pregnancy was related to grandchild ASD (aRR = 1.76, 95% confidence interval [1.05, 2.96]), as was grandfathers' cigarette smoking (aRR = 1.67 [1.01, 2.76]), particularly smoking 20 or more cigarettes per day (aRR = 1.91 [1.03, 3.55]), relative to no smoking. Alcohol consumption of five or more drinks of hard liquor per week by grandfathers was associated with ASD in grandchildren (aRR = 2.90 [1.24, 6.79], relative to none), as was total consumption of nine or more total alcoholic drinks (aRR = 1.87 [1.00, 3.51] relative to < 9). Coffee consumption and combined coffee and tea consumption by either grandparent were not associated with grandchild ASD. Findings support the hypothesis that grandfather exposures around the time of offspring conception are linked to grandchild autism.