Cannabis Use in Peri-Pregnancy and Autism Spectrum Disorder in the Offspring: Findings from the Study to Explore Early Development
Objectives: To determine whether ASD is associated with maternal cannabis use during the 3 months prior to conception or during pregnancy.
Methods: The Study to Explore Early Development (SEED) is a US multi-site case-control study of children aged 30-68 months born in 2003-2006 (SEED1) or 2008-2011 (SEED2). ASD cases (n=1397) were determined using standardized ASD-specific diagnostic instruments including the Autism Diagnostic Observation Schedule and the Autism Diagnostic Interview-Revised. General population controls (n=1586) were recruited from randomly sampled birth certificates. Each child’s mother was interviewed by telephone after enrollment and asked about her marijuana (cannabis) use in each month from 3 months prior to conception through delivery (“peri-pregnancy”). Associations between maternal cannabis use and ASD in her offspring were examined using a generalized linear mixed model, including site as a random effect, adjusted for demographics, other substance use (tobacco, alcohol, illicit drugs), and enrollment period.
Results: Maternal peri-pregnancy cannabis use was reported for 5.4% of children with ASD and 4.5% of control children. Prevalence among maternal cannabis users declined in both the ASD and control groups from preconception (95% and 83%, respectively) to the first trimester (48% in both groups) to the third trimester (11% and 13%, respectively). Peri-pregnancy cannabis use was associated with lower caregiver education level, lower household income, and higher use of tobacco, alcohol and illicit drugs during pregnancy. In adjusted analyses, the odds of cannabis use in the peri-pregnancy period were not significantly different between cases and controls (adjusted OR [aOR] = 0.82 [95%CI: 0.55, 1.20]), nor was there a significant interaction between peri-pregnancy cannabis use and tobacco use in their association with ASD (p=0.30). There were also no associations observed between ASD and cannabis use in the three months prior to conception (aOR=0.99 [0.66, 1.49]) or during pregnancy (aOR=0.74 [0.44, 1.23]).
Conclusions: ASD in the offspring was not significantly associated with maternal use of cannabis in the peri-pregnancy period in these data. However, cannabis use was uncommon (consistent with national data), limiting study power, and we lacked information about route of ingestion, dose, and frequency of cannabis use. Further, we did not find evidence that cannabis and tobacco use together have a greater effect on the odds of ASD, as has been previously reported. With medicinal and recreational cannabis increasingly becoming decriminalized or legalized in many states, larger, longitudinal studies with more detailed information on frequency, amount and mode of intake are needed to establish whether any association exists between cannabis use and ASD risk.