Breastfeeding persons are encouraged to avoid using marijuana. The health effects of a breastfeeding person’s use of marijuana on her infant are not yet fully known, and the available data are limited and conflicting. However, we know that chemicals from marijuana can be passed to a baby through breast milk. In addition, tetrahydrocannabinol (THC) is stored in body fat and is slowly released over time, meaning that a baby could still be exposed even after a breastfeeding person stops using marijuana.
 Ryan SA, Ammerman SD, O’Connor ME. Marijuana use during pregnancy and breastfeeding: implications for neonatal and childhood outcomes. Pediatrics. 2018;142(3).