Please use this link to access this publication: https://www.nature.com/articles/s41390-022-02315-1 Abstract Background Cannabis is often used by women to manage symptoms of morning sickness during pregnancy, and postpartum stress and anxiety. While exclusive breastfeeding has been recommended for the first 6 months of an infant’s life, the presence of cannabinoids in the milk of cannabis users complicates this recommendation. The objective of this study was to investigate the effect of maternal cannabis use on changes in the levels of macronutrients and bioactive factors in breast milk. Methods Milk was collected from women who were 6–8 weeks postpartum and were either using cannabis post-delivery, had used cannabis...