Cannabis use, including among among pregnant women, is rising sharply in the US. Media and even government outlets seem in a rush to promote it as a side-effect free answer to stress, anxiety and other conditions. But does its use by expectant mothers pose a risk to their unborn children?
Recreational cannabis use for adults is now legal in 11 states and Washington, DC. Pregnant women comprise one of the fastest-growing groups of cannabis users in the US. Now, a group of researchers at Washington University in St. Louis have looked at the effects of cannabis use by expectant moms on their children as they grow into middle childhood.
Unfortunately, what they found should give pause to any pregnant woman about to light up. The children of pregnant cannabis users are more likely to have psychopathology during middle childhood.
“There have been increasingly permissive and lenient attitudes toward cannabis use among pregnant people,” said Sarah Paul, a clinical psychology graduate student. “It has skyrocketed in the past few years,” she added, with data indicating a quick rise from 3% to 7% past-month use.
“Unfortunately, despite the increase in use, we know remarkably little about the potential consequences of prenatal cannabis exposure,” Paul said. “Prior studies have linked prenatal cannabis exposure to birth-related outcomes such as lower birth weight and infant characteristics like disrupted sleep and movement. Relatively fewer studies have examined behavior and problems as children age,” and, she said, “findings have been tenuous due to inconsistent replication and an inability to account for potential confounding variables.”
The research team also included Alexander Hatoum, a postdoc research scholar and Ryan Bogdan, who is an associate professor of psychological and brain sciences at Washington University and is also head of the Brain Lab there. With the rest of the team, they examined mounds of data to determine what kind of effects cannabis use by pregnant moms would have on their children.
The study and its’ findings were published on September 23, 2020 in JAMA Psychiatry.
Their primary data source was the Adolescent Brain and Cognitive Development Study, or ABCD Study. This is an ongoing longitudinal study of almost 12,000 children between the ages of 9 and 11, along with their parent or caregiver. It began in 2016 and includes 22 sites across the USA.
The team placed participants in one of three mutually exclusive groups. These were 1. children who were not exposed to cannabis prenatally; 2. children who were exposed prenatally before the pregnancy was known, but not after; and 3. children who had been exposed to cannabis after the pregnancy was known, without regard to exposure before.
It’s generally believed that the receptors influenced by cannabis are not expressed before about 5 to 6 weeks into a pregnancy. It was expected by the researchers that associations with the children’s outcomes would only be notable if the cannabis exposure occurred once the receptors had been expressed. For most of the participants, it was reported that they learned of being pregnant at or after about 7 weeks. This lines up with the time after which the receptors, called endocannabanoid type 1 receptors, had been expressed.
The hypothesis was that regardless of the time of occurrence, prenatal exposure to cannabis would lead to adverse outcomes in childhood. However, only continued exposure after the pregnancy was known would lead to an independent association with those adverse outcomes.
The team factored in potential confounds like use of prenatal vitamins, alcohol and tobacco use, family history of psychopathology, whether the children had used alcohol and others.
Cannabis exposure in the womb, regardless of when, led to a slightly higher likelihood of adverse childhood outcomes. These children experienced more social problems, sleep disturbances, problems with attention and impulsivity as well as anxiety and depression. Other noted adverse outcomes included lower birth weights, lower indices of global brain structure and lower cognitive performance during middle childhood.
But when the research team included important familial, pregnancy and child-related covariates, Bogdan said, “This is when things got really interesting. All associations with prenatal exposure only prior to maternal knowledge of pregnancy were nowhere near significantly associated.” This suggests that the association between prenatal cannabis exposure during early stages of pregnancy may not be independent of these confounding factors.
“However, when we look at exposure after maternal knowledge of pregnancy, which corresponds to when endocannabinoid type 1 receptors are expressed in the fetal brain, the associations with child psychopathology largely remain — these children tend to have more psychotic-like experiences, more impulsivity and attention problems, and social problems,” he said. “This raises the intriguing possibility that prenatal cannabis exposure may plausibly impact child behavior. It in no way shows causation, but documenting that effects are independent of common confounding factors provides incremental support for potential causation.”
“There are certainly other plausible reasons for this pattern of results,” Hatoum said. It could be that the behaviors are a byproduct of genetic and environmental similarity and not connected causally to cannabis use.
“However, that our measures of these potential confounds accounted for the associations with use prior to maternal knowledge, but not after, suggests that prenatal cannabis exposure may independently contribute, in a small way, to child outcomes,” he said. “Potential causation underlying this association should be further evaluated using experimental non-human animal models, additional replication and other approaches (e.g., siblings discordant for exposure).”
“Cutting to the chase, my interpretation of these findings, is that clinicians and dispensaries should discourage cannabis use among those who are pregnant or are considering becoming pregnant,” Bogdan said.
“Being attentive to substance use problems among family members and providing them with support and access to help is critical for anyone regardless of pregnancy status,” Bogdan said. “Learning of one’s pregnancy may produce additional reason to stop use. Someone who has just learned of a pregnancy and has previously used cannabis, might think, well I have already exposed the fetus to cannabis, so I may as well not stop. The current data might provide the clinician and parent-to-be with evidence that stopping after learning of the pregnancy may reduce the likelihood of negative outcomes among their children.”
At the same time, Bogdan said, “It is also important not to stigmatize expecting parents who may be experiencing difficulties. Quitting substance use during pregnancy, which is already a challenging time, may not be straightforward. Physician support and empirical paradigms for quitting during pregnancy will be important. Lastly, couples who are planning to have a child may wish to consider combating cannabis use before they begin attempting to conceive and the additional stressors of pregnancy begin to mount.”
Bogdan thinks that, from a public health perspective, there is a highly effective campaign to mimic in improving outcomes for pregnant mothers. The public health campaign to reduce the use of tobacco and alcohol by expectant mothers provides a framework and correlates strongly with the cannabis issue. He also thinks reducing cannabis use among pregnant mothers may be more important than reducing alcohol or tobacco use.
In fact, he said, “This study found that prenatal cannabis exposures were more strongly and consistently associated with adverse child outcomes than prenatal tobacco or alcohol exposure.”
As we rush headlong to make weed mainstream, we may want to stop along the way and ask who might be hurt by our actions and what unforeseen circumstances and outcomes are possible.
After all, our kids might be counting on us!
Keep the faith and keep after it!
Journal Reference – Sarah E. Paul, Alexander S. Hatoum, Jeremy D. Fine, Emma C. Johnson, Isabella Hansen, Nicole R. Karcher, Allison L. Moreau, Erin Bondy, Yueyue Qu, Ebony B. Carter, Cynthia E. Rogers, Arpana Agrawal, Deanna M. Barch, Ryan Bogdan. Associations Between Prenatal Cannabis Exposure and Childhood Outcomes. JAMA Psychiatry, 2020; DOI: 10.1001/jamapsychiatry.2020.2902