Maternal cannabis use linked to genetic changes in babies

Novel research suggests cannabis use during pregnancy is directly linked to negative impacts on babies’ brain development.

Led by Te Whare Wānanga o Waitaha | University of Canterbury (UC) School of Biological Sciences Senior Lecturer Dr. Amy Osborne, the study, for the first time, has found that prenatal cannabis use is associated with molecular changes in the genes of exposed children.

“We know cannabis use during pregnancy is associated with childhood and adolescent brain development and cognitive function,” Dr. Osborne says. “However, previous studies haven’t been able to prove that cannabis exposure has specifically caused the adverse effects on neurodevelopment that have been observed.”

The research is published in the journal Molecular Psychiatry.

Dr. Osborne says the new study is important because cannabis use during pregnancy is a growing issue: “Cannabis is now the most commonly used drug, excluding alcohol and tobacco, among pregnant women in the United States and the frequency has been rising since the COVID-19 pandemic.”

The research, which is a collaboration between UC and the University of Oxford, in the United Kingdom, uses genomic data from two longitudinal studies; the Avon Longitudinal Study of Parents and Children in the UK, and the Christchurch Health and Development Study. The findings reveal genome-wide significant DNA changes in the offspring of mothers who smoked cannabis during pregnancy.

“Using data from individuals at birth, aged seven, 15-17, and 27, we showed a molecular signature of prenatal cannabis exposure (PCE) in exposed individuals,” Dr. Osborne says. “In a world-first, we identified a significant number of molecular changes in genes involved in neurodevelopment and neurodevelopmental disease, across the life course. This is a key finding because it suggests there is a molecular link between prenatal cannabis exposure and impacts on the genes involved in neurodevelopment.”

Dr. Osborne says the results add to growing evidence suggesting a causative link between PCE and adverse outcomes in exposed children.

This is of serious concern, because internationally, many pregnant women are using cannabis and cannabis-containing products to alleviate pregnancy symptoms and anxiety, she says.

“With the wider availability of cannabis products overseas, and eventually in New Zealand, the use of cannabis during pregnancy will continue to rise. However, the harms of this practice are not well known.

“We hope our research will inspire further investigation with larger cohorts and there will soon be clearer advice to pregnant women about the impact of cannabis use. Otherwise, the potential risk to children remains, and will likely grow.”