— "Another piece of the puzzle" of how marijuana use affects childhood outcomes
Children exposed to marijuana in utero had a moderately elevated risk of developing autism spectrum disorder, according to a Canada-based retrospective study.
Mothers who used cannabis while pregnant had a 50% higher likelihood of having a child with autism (adjusted hazard ratio 1.51, 95% CI 1.17–1.96), reported Daniel Corsi, PhD, of Ottawa Hospital in Ontario, and colleagues.
Hints of increased risk of intellectual and learning disabilities and attention deficit hyperactivity disorder (ADHD) were also seen, according to their paper in Nature Medicine.
Nevertheless, said Corsi in an email to MedPage Today ,"[o]ur clinical recommendation based on these findings is for women who are pregnant or thinking of becoming pregnant to avoid the use of cannabis products."
Torri Metz, MD, a maternal-fetal medicine specialist at the University of Utah, commented that this study adds to previous concerns about prenatal marijuana exposure's potential effects on offspring.
"It is another piece of the puzzle," Metz, who was not involved in this research, told MedPage Today. "It makes us worry about cannabis exposure in utero and whether it is influencing fetal neurodevelopment." Metz also underscored the importance of interpreting these findings with caution, as this large population-based study was limited in its classification of substance use.
Lauren Jansson, MD, the director of pediatrics at the center for addiction and pregnancy at Johns Hopkins Bayview Medical Center, said that she hopes this study will further encourage clinicians to counsel patients to avoid marijuana use, not only during pregnancy, but while breastfeeding as well.
"We know that medical providers often tend to discount cannabis use as unimportant, and we know that counseling -- even during pregnancy -- is inconsistent," Jansson, who was not involved in this study, said in an interview. "With studies like this, it's more data that will support recommendations for women to at least stop using in pregnancy."
Using the Ontario Better Outcomes Registry & Network (BORN), researchers examined the association between cannabis exposure and risk of neurodevelopmental disabilities. They analyzed more than 500,000 births that occurred between 2007 and 2012, and followed children for up to 10 years. In this group were 3,148 mothers who used cannabis (0.6%).
The researchers also found trends toward increased incidence of intellectual and learning disabilities (HR 1.23, 95% CI 0.97–1.55), as well as ADHD (HR 1.11, 95% CI 0.99–1.25) in the matched cohort among children whose mothers used marijuana. These remained nonsignificant after further adjustment.
"We certainly need more information about marijuana use and downstream effects for offspring who are exposed in utero," Metz said. "It's exciting to see that people are evaluating this."
Primary Source: Nature Medicine - Source Reference: Corsi D, et al "Maternal cannabis use in pregnancy and child neurodevelopmental outcomes" Nature Medicine 2020; DOI: 10.1038/s41591-020-1002-5.