In the US, cannabis is now the most commonly used federally illegal drug in pregnancy, with an incidence of 7% among pregnant individuals in 2017, an increase from 3.4% in 2002. More recently, significantly increased rates of use by pregnant individuals have been reported, coinciding with the COVID-19 pandemic, with a prevalence of use up to 25% in some areas such as northern California
A recently published journal out of the Oregon Health and Science University reported that prenatal cannabis use was associated with changes to the genome and RNA transcript of the placenta, which also doubles as a mediator risk for anxiety-related problems in early childhood. Authors noted emergent data, including from ongoing including from the ongoing longitudinal Adolescent Brain and Cognitive Development study, highlighting that in-utero cannabis exposure is connected to adverse outcomes such as babies being small for gestational age, neonatal intensive care unit admissions, and preterm birth.
In addition, prenatal cannabis exposure has also been associated with childhood outcomes such as autism spectrum disorder and attention-deficit/hyperactivity disorder and symptoms of psychopathology, including psychotic-like experiences, internalising, externalising, attention problems, and thought and social problems. Maternal cannabis use disorder has also been linked to a greater risk of small for gestational age, preterm birth, low birth weight, and death within 1 year of birth.
The article also reported recent data showing paternal cannabis use preconception can also affect reproductive health and offspring outcomes. This includes lower infant birth weight, higher risk of spontaneous abortion and sudden infant death syndrome. The data also highlighted that paternal cannabis exposure in both humans and nonhuman primates is associated with altered sperm DNA involved in neurodevelopment and autism spectrum disorder. The authors also noted a lag in public health efforts to caution against cannabis use while pregnant, possibly due to the lack of definitive evidence of harm with use.
As the evidence of deleterious effects from prenatal cannabis use continues to accumulate, physicians and researchers in reproductive health have a responsibility to mitigate adverse health outcomes from perinatal cannabis use. Fulfilling this responsibility requires actionable evidence from high-quality research to guide healthcare clinician counselling, inform developmental screening strategies for exposed offspring, direct health policies, and garner public awareness.
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Check out our factsheets on the harms of cannabis use and pregnancy.