Cannabis in pregnancy: What brain scans reveal—and what's still unclear

This narrative review examines recent research on how prenatal cannabis exposure (PCE) affects fetal and childhood brain development, analyzing studies published after 2019 that used advanced brain imaging techniques. Researchers reviewed 9 studies using MRI technology to track brain changes from pregnancy through adolescence, finding that PCE was associated with differences in frontal, parietal, and temporal brain regions—areas critical for decision-making, sensory processing, and memory. The findings suggest potential impacts across multiple stages of development, but importantly, the research reveals no consistent pattern yet about exactly how cannabis exposure shapes the developing brain.

The review highlights significant limitations in current research that complicate drawing firm conclusions. Scientists face challenges including varying methods of measuring cannabis use (self-report versus biological testing), difficulty isolating the effects of cannabis from other prenatal exposures, and incomplete information about timing, frequency, potency, and consumption method. Additionally, only 3 of the 9 studies examined both brain imaging and actual behavioral outcomes, making it difficult to understand whether observed brain differences translate to real-world developmental consequences. The authors stress that parental and postnatal factors—such as childcare environment and parenting style—weren't adequately controlled for in most studies.

The authors call for more rigorous future research with standardized assessment methods and designs that can capture the complexity of real-world cannabis use during pregnancy. Such research is increasingly urgent given rising cannabis use among pregnant individuals and changing legal/social attitudes toward cannabis. Only through better-designed studies can we understand whether prenatal cannabis exposure causes lasting effects on child development or whether observed brain imaging differences have meaningful health implications for growing children.