Babies exposed to cannabis more likely to be born preterm

Cannabis use during pregnancy heightens the risk of adverse birth outcomes such as preterm birth, low birth weight, and requiring neonatal intensive care unit (NICU) care, according to a new study in the journal Addiction.

However, they are not at greater risk of birth defects or death within one year, including sudden unexpected infant death, compared to infants without prenatal cannabis exposure.

The research pooled the results of 57 prior studies published between 1984 and 2023. This included data from almost 13 million infants, of which more than 102,000 had intrauterine cannabis exposure.

Mothers using cannabis were over 1.5 times more likely to have a preterm delivery, and more than 2 times as likely to have a low-birth-weight baby, compared with mothers not using cannabis during pregnancy.

Cannabis exposed newborns were also more than 2 times as likely to require NICU admission than nonexposed newborns.

Maryam Sorkhou, first author of the study and PhD candidate at the at the Institute of Medical Science, University of Toronto, Canada, says: “The global increase in cannabis use among women of reproductive age also extends to pregnant women.”

“We know that THC, the main psychoactive constituent in cannabis, can cross the placenta from mother to foetus and bind to receptors in the foetal brain. 

“Our study adds to that knowledge by showing that prenatal exposure to cannabis heightens the risk of several adverse birth outcomes.”

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