Associations of Prenatal Cannabis Exposure and Neonatal Brain Development in the HBCD Cohort

<b>Question:</b> Is prenatal cannabis exposure associated with brain development in the first month of life?<b>Findings:</b> In a cohort of 1,782 mother-infant dyads, prenatal cannabis exposure was associated with region-specific differences in neonatal brain volumes. Brain volume and diffusion white matter microstructure associations differed between exposure limited to the first trimester versus exposure that continued into the third trimester. Greater frequency of exposure across gestation was also associated with volumetric and microstructural differences.<b>Meaning:</b> The timing and frequency of prenatal cannabis exposure is associated with alterations in neonatal brain development, underscoring the importance of addressing cannabis use in pregnancy.