When it comes to cannabis legalization, two consistent concerns among regulators and lawmakers are use by minors and pregnant individuals. While there’s no Food and Drug Administration-approved cannabinoid-based medication to treat symptoms during pregnancy, cannabis is “most commonly used during the first trimester, and by women with severe nausea,” according to the National Institute on Drug Abuse (NIDA).
A study published on Thursday in the peer-reviewed journal Addiction provides greater insight into how cannabis use disorder affects pregnancy, finding “significant associations between prenatal [cannabis use disorder] exposure and major adverse neonatal outcomes.”
For the study, researchers analyzed live birth data recorded in California between the years 2001 to 2012, a time during which the state’s permissive medical cannabis program boomed, though adult use was not yet legal. Of the almost 5 million births, researchers found that the babies born to people who self-reported cannabis use disorder were linked to early birth and lower birth weights when compared to parents who did not report cannabis use disorder. The study was funded by NIDA.
The study concluded that “prenatal [cannabis use disorder] was associated with major adverse neonatal outcomes, including greater odds of small for gestational age, preterm birth, low birth weight, and death within 1 year of birth.” The effects were more prominent in pregnant people who used both cannabis and nicotine, and also in minority groups.
It is worth noting that the study found an association, not causation. “Because we are looking only at medical records, there is a lot we don’t know about the mothers and infants in this study,” lead author Yuyan Shi of the Herbert Wertheim School of Public Health and Human Longevity Sciences at the University of California, San Diego, said in a statement.
Nora Volkow, director of NIDA at the National Institutes of Health, echoed this sentiment in a statement that researchers “cannot establish that cannabis use caused negative outcomes in this study.” Still, Volkow told Cannabis Wire that the research confirms prior findings “indicating that there are significant changes in neonates borne out of mothers who consume marijuana.” But, Volkow told Cannabis Wire, the finding of “increased mortality did surprise me.”
Volkow pointed to alcohol and noted that for years people weren’t truly aware of the serious effects on a newborn that alcohol consumption during pregnancy could have.
“Already, with the data that we have, we can put in a strong recommendation about not smoking marijuana during pregnancy, because we know already through all of these studies, and this one, that it can have a negative effect on the newborn,” Volkow told Cannabis Wire.
Still, more research is needed to, for example, better understand the mechanisms of how cannabis affects newborns, and which organs are implicated and to what extent.
Meanwhile, though, as states continue to implement new medical and adult use cannabis laws, Volkow said that the issue of cannabis use during pregnancy “deserves much stronger regulation from the state.”
When asked if lawmakers or regulators had been in touch with Volkow or her office, Volkow said that cannabis use during pregnancy hasn’t gotten the same level of inquiry as youth use.
“There has been much more attention to the use of marijuana by adolescents. But attention to the use of marijuana during pregnancy has not been at the forefront,” she said.
This research adds to previous research that found that cannabis “may” be linked to poorer birth outcomes.
The study had several limitations, including the potential for reluctance to self-identify a cannabis use disorder, especially considering the study took place ahead of full legalization in California, and generally less accepted. Researchers note that the parents who did self-report might have been on the more severe side of cannabis use disorder-related symptoms, and that potential reluctance to self-report “might become less” post legalization.
Last January, the House Energy and Commerce Subcommittee on Health held a hearing called “Cannabis Policies for the New Decade” during which Volkow fielded questions and testified before members. Volkow spent much of her testimony explaining how cannabis works in the body, and highlighted two main concerns: cannabis use by pregnant people, and youth use.
Cannabis use during pregnancy is linked to lower birth weight and preterm deliveries, Volkow said.
“In adolescence, cannabis use has been consistently associated with lower academic achievement, higher risk of dropping out of school, lower IQ, disruptions in brain connectivity and structure as the brain transitions into adulthood,” Volkow said.
During a 2019 Senate Caucus on International Narcotics Control hearing called “Marijuana and America’s Health: Questions and Issues for Policy Makers,” Volkow and former US Surgeon General Jerome Adams spoke about use among youth and pregnant individuals, among other topics.
Volkow pointed out during her testimony that while research is underway to examine the effects of THC on growing fetuses, one reason that cannabis poses harm to fetuses is that THC “freely crosses the placenta.” She added that “fetal exposure is associated with significant negative outcomes, including fetal growth restriction, lower birth weight and preterm delivery.”
