using cannabis for nausea while pregnant boosts behavioural risk

get healthing in your inbox with the morning checkup and weekender newsletter!

new research suggests that using cannabis while pregnant may increase your future child’s risk of developing psychotic-like behaviour.

by emma jones

published sep 25, 2020

last updated feb 20, 2025

2 minute read

join the conversation

2 minute read

join the conversation

getting high while pregnant could cause more problems than it solves

health canada advises against the use of cannabis products during pregnancy and breastfeeding. getty

bad news for expectant mothers who turn to marijuana to treat morning sickness.

new research suggests that using cannabis while pregnant may increase your child’s risk of developing psychotic-like behaviour.

researchers from washington university looked at data collected by the adolescent brain and cognitive development (abcd) study, a health database of 11,875 children, parents’ health information, and pregnancy data. of this sample set, 655 children were found to have been exposed to cannabis prenatally.

compared to children whose mothers had no exposure to cannabis, use of these products while pregnant was correlated with greater behavioural concerns in the developing child — such as psychotic-like experiences; attention, thought, and social challenges, greater sleep problems, greater body mass index (bmi), lower cognition and less grey matter (regions that have high concentrations of neurons or brain cells).

cannabis already shown to affect a developing child

the psychoactive component of cannabis, tetrahydrocannabinol (thc), is able to cross the placenta where it may interfere with the developing brain of the fetus. scientists are not sure exactly how the active ingredients in marijuana affect the developing fetus, but previous studies have linked its presence to a greater risk of the baby being born prematurely or at a lower weight.

endocannabinoid receptors — the parts of the brain thc attaches to and produces the characteristic effects of getting high — begin to develop around five to six weeks gestation. in this study, researchers roughly correlated this time frame with when the mothers in the abcd study found out about their pregnancy (on average, at 6.9 weeks), and divided the sample of children whose mothers used cannabis during pregnancy into two groups: 413 children were only exposed to cannabis before the mother knew she was pregnant (roughly before the endocannabinoid receptors formed), and 242 were exposed after the mother knew she was pregnant.

once researchers factored in other variables, like socioeconomic status and health data of the parents, exposure to cannabis products after the mother knew she was pregnant was still correlated with psychopathology concerns in the child. however, this correlation was largely reduced in children who were only exposed to cannabis before the six-week gestation mark.

health canada warns that cannabis is not safe for consumption at any point during pregnancy and advises against its use in treating morning sickness or other medical conditions during pregnancy.

mothers experiencing morning sickness are advised to speak to their doctors for information on treatments that are less risky for the baby.

“until more is known about the short and long-term effects of cannabis, it is safest to avoid using cannabis when pregnant and breastfeeding,” according to health canada. “there is no known safe amount of cannabis use during pregnancy.”

emjones@postmedia.com | @jonesyjourn

don’t miss the latest on covid-19, reopening and life. subscribe to healthing’s newsletter coming out of covid for daily updates on the top 世界杯决赛2022 and the healthing weekender delivered to your inbox on saturday.