A study recently published in the journal Addiction found that infants exposed to cannabis in the womb are more likely to be born prematurely, have lower birth weights, and need care in a neonatal intensive care unit (NICU) compared to those not exposed to cannabis prenatally. The study also noted that these cannabis-exposed infants do not have a higher risk of birth defects or of dying within their first year, including from sudden unexpected infant death.
First author Ms. Maryam Sorkhou comments, “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 fetus and bind to receptors in the fetal brain. Our study adds to that knowledge by showing that prenatal exposure to cannabis heightens the risk of several adverse birth outcomes.”
Methodology of the Meta-Analysis
This meta-analysis (a synthesis of past studies) pooled the results of 57 prior studies with a total of 12,901,376 infant participants, 102,835 of them exposed to cannabis.
Twenty of the studies measured the association between intrauterine cannabis exposure and the risk of preterm delivery. In these, the combined results show that mothers using cannabis were over one and a half times more likely to have a preterm delivery compared with mothers not using cannabis during pregnancy.
Eighteen of the studies measured the risk of low birth weight. In these, the combined results show that mothers using cannabis during pregnancy were more than twice as likely to have a low-birth-weight baby compared with mothers not using cannabis during pregnancy.
Ten of the studies measured the risk of requiring NICU admission. In these, the combined results show that newborns with intrauterine cannabis exposure were more than twice as likely to require NICU admission than nonexposed newborns.
The studies included in this meta-analysis were published between 1984 and 2023 in a broad range of countries.
Reference: “Birth, cognitive and behavioral effects of intrauterine cannabis exposure in infants and children: A systematic review and meta-analysis” by Maryam Sorkhou, Daisy R. Singla, David J. Castle and Tony P. George, 15 November 2023, Addiction.
The study was funded by the Centre for Addiction and Mental Health, National Institute on Drug Abuse.