UC Davis

The California Department of Developmental Services (DDS) (2003) reported that children with Autism Spectrum Disorder (ASD) are being recognized at accelerated rates. These increases in prevalence cannot be fully attributed to changes in diagnostic criteria, improvements in detection, or population increases. Maternal substance use is one area of environmental risk under study. Of these substances, cannabis remains one of the most used by pregnant mothers. Cannabis, referring to the component of the plant cannabis sativa that contains >0.3% delta-9-tetrahydrocannabinol (THC), has been identified as a developmental toxicant. The psychoactive cannabinoid–THC–can be passed from mother to fetus via the placenta or to the child through breastfeeding. THC has been implicated in affecting a child’s developing endocannabinoid system, and ultimately affects a child’s neurodevelopment. This is concerning as the THC content of cannabis products has increased with increased legalization and evolving markets. This study sought to examine the association between maternal cannabis use before or during pregnancy and the odds of ASD diagnosis in 1,152 children from the Childhood Autism Risk from Genetics and the Environment (CHARGE) study, a large population-based case-control study with data from over 20 counties. The crude model indicated an association in the direction of increased risk with low precision (OR=1.28; 95%CI=0.81-2.01). After adjustment for mother’s age at delivery, maternal experience of stress, family history of ADHD, maternal intake of folic acid supplements during pregnancy, presence of any smokers in the house before or during pregnancy, protective socioeconomic factors, maternal use of non-cannabis recreational drugs and tobacco products, and year of birth, the effect was moved toward the null (OR=1.20; 95%CI=0.68, 2.12). However, the lack of significant results does not confirm that maternal cannabis use does not increase odds of ASD. Further studies are needed on more recent cohorts given the increased THC potency, accessibility of cannabis products, and changing attitudes toward use during pregnancy.