Cannabis and pregnancy

In a multicenter observational cohort study (1):

• a composite adverse pregnancy outcome (small-for-gestational-age birth, medically indicated preterm birth, stillbirth, or hypertensive disorders of pregnancy) was more frequent in pregnant individuals with cannabis exposure ascertained by a urine drug assay (25.9%; n = 610) compared with unexposed individuals (17.4%; n = 8647)
• risk for an adverse outcome was higher among those who continued to use cannabis beyond the first trimester
• study authors concluded:
  • cannabis use should be avoided during pregnancy to optimize maternal and neonatal outcomes

A review notes (2):

• in utero exposure to marijuana has been linked to a “withdrawal”-like syndrome in newborns, demonstrated by an increase in startles and tremors and reduced habituation to light
• tetrahydrocannabinol is a fat-soluble molecule excreted in human breast milk in moderate amounts
  • in chronic heavy users, the milk-to-plasma ratio can be as high as 8:1 and metabolites of cannabis are found in infant feces and urine, suggesting that it might be absorbed and metabolized by the infant

Reference:

• Metz TD, Allshouse AA, McMillin GA, et al. Cannabis Exposure and Adverse Pregnancy Outcomes Related to Placental Function. JAMA. 2023;330(22):2191–2199. doi:10.1001/jama.2023.21146
• Badowski S, Smith G. Cannabis use during pregnancy and postpartum. Can Fam Physician. 2020 Feb;66(2):98-103.