Cannabis is widely used for recreational and medical purposes with usage increasing rapidly following its legalization in parts of the world[1]. While there are well-documented effects of cannabis on the users themselves, the impact of its consumption during pregnancy on offspring is much less clear. Previous studies have reported that maternal cannabis usage during pregnancy is associated with lower birth weight and there is the suggestion of impaired neurodevelopment in both observational cohorts in humans and experimental studies in animal models[2-7]. However, how maternal cannabis exposure leads to these adverse health outcomes in offspring remains unclear.
Epigenetic mechanisms play an important role in regulating gene expression and cell homeostasis. Previous experimental studies showed that DNA methylation in offspring could be modified by maternal cannabis exposure[8-10]. In some cases this leads to dysregulation of the immune system of the fetus[11-13]. However, no human studies have yet been conducted, and no specific epigenetic signatures have been identified related to cannabis exposures. We hypothesize that maternal cannabis exposure during pregnancy alters the epigenetic profiles and leads to a specific epigenetic signature of the fetus through in utero exposure, and the epigenetic alterations can then lead to impaired neurodevelopment in the offspring. Therefore, we propose to investigate the association of maternal cannabis exposure around the time of pregnancy with DNA methylation profiles in offspring at birth in the ALSPC cohort.