Presents the latest clinical evidence on how cannabis use during pregnancy and breastfeeding can affect a developing fetus and infant. Key points include: the effects of cannabis can be passed onto the fetus through the placenta or onto the baby through breastmilk, exposure to cannabis can impact the baby’s mental and physical development, and there is not enough evidence to support using cannabis to treat morning sickness nor pain. Healthcare providers will find this resource helpful for advising patients. Researchers will also find it useful for understanding gaps in the knowledge needed to support harm reduction efforts for this population.

Key points:
• Cannabis is the second-most common psychoactive substance (after alcohol) used during pregnancy.
• Elements of cannabis can pass through the placenta and affect the fetus’s development. Frequent cannabis use during pregnancy is associated with low birth weight and is part of a cluster of risk factors related to other adverse birth outcomes.
• There are also affects on behaviour in children and young adults, including attention deficits, emotional disturbances, increased hyperactivity and impulsivity, sleep disorders, and increased likelihood of substance use.
• Growing evidence from human and animal studies shows that paternal cannabis use can also negatively affect children’s neurodevelopment.
• Elements of cannabis can pass into breastmilk during lactation, which the infant absorbs and metabolizes.
• The effects of cannabidiol (CBD) use during pregnancy or breastfeeding are unknown. Both clinical and preclinical studies are urgently needed to evaluate the safety of CBD use during pregnancy.
• Information on the effects of cannabis use during pregnancy is essential to help healthcare providers advise patients about the effect of cannabis use and improve the health and well-being of patients and their children.
• Pregnant or breastfeeding parents should have informed discussions with healthcare providers about the potential adverse effects of cannabis use during pregnancy to help them better understand the potential risks and help them make informed and healthy choices.