Weed Use During Pregnancy Is Linked to Psychotic Tendencies in Kids, Finds Study

A massive long-term study of almost 11,500 kids shows those who were exposed to weed in the womb were more likely to have aggression towards others, as well as weaker cognitive abilities.
September 28, 2020, 12:51pm
pregnant woman
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A new study has revealed that women who use weed while pregnant might have children who are more prone to showing psychotic-like behaviours. There may be unexpected impacts of using weed in any form, says this study under the Adolescent Brain Cognitive Development study, published on September 23. 

The study, which says it is the "largest long-term study of brain development and child health in the United States”, analysed data on 11,489 children. Of those children, 655 were exposed to cannabis while in utero, according to statements from the mothers. 

The behaviours and cognitive patterns of the children were evaluated in middle childhood, around the time they were nine years of age. Compared to the 10,834 children with no exposure, children whose mothers had used during pregnancy were more likely to have aggression towards others, as well as attention and social problems—they showed psychotic-like behaviours and more sleep problems, as well as weaker cognitive abilities. 

The study, published in JAMA Psychiatry, reveals that if the mother continued to consume cannabis after she discovered she was pregnant, the negative effects were more pronounced. Children who were exposed before a mother's knowledge of pregnancy, but not after, showed no differences to those children that were not exposed at all.

The first trimester may be one of the most sensitive times for the developing brain of a foetus when it's most susceptible to damage. Not only does THC—the compound in marijuana that makes you high—enter the fetal brain from the mother's bloodstream, but once there, it can also impact the baby's developing brain. "THC has been found in breast milk for up to six days after the last recorded use," states an advisory given by the Surgeon General in the U.S. last year. After all, studies have found receptors for cannabis in the brains of animals as early as five and six weeks of gestational age.

Whether or not this link is causal is not clear; there are many other factors the researchers may not have considered. But in the context of other research, it's an interesting link worthy of further exploration. Several other lines of evidence have also shown prenatal cannabis exposure is associated with decreased attention span and some behavioural problems in children.

The vast majority of marijuana use was during the first three months of pregnancy, the study found, and it was predominantly recreational rather than medical. The use of marijuana by pregnant women has been growing in the United States and other countries such as Canada in recent decades. A 2019 analysis found cannabis use more than doubled between 2002 and 2017.

Cannabis is reportedly used by women in their pregnancy to deal with nausea and vomiting in early pregnancy, but there's little evidence to say whether this works or if it's safe. As such, there is currently no known safe level of cannabis use during pregnancy or lactation. 

Past studies have shown the use of marijuana during pregnancy is linked to low birth weight, impulsivity, attention issues, and other cognitive and behavioral issues in children, according to the U.S. Centers for Disease Control and Prevention. There's even a connection to autism.

But while research on the health effects of cannabis is slowly catching up with legalisation, data on cannabis use during pregnancy is still lagging far behind. Alcohol and tobacco during pregnancy are also linked to adverse health outcomes, but in comparison to cannabis, these are already well documented.

Until we have those answers, researchers say healthcare professionals should discourage those who are pregnant, breastfeeding, or even contemplating having kids from using cannabis.

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