Obstetrics| Volume 41, ISSUE 9, P1311-1317, September 2019

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Cannabis Use in Pregnancy in British Columbia and Selected Birth Outcomes

Published:February 07, 2019DOI:



      This study sought to determine the association between cannabis use in pregnancy and stillbirth, small for gestational age (SGA) (<10th percentile), and spontaneous preterm birth (<37 weeks).


      The study used abstracted obstetrical and neonatal medical records for deliveries in British Columbia from April 1, 2008 to March 31, 2016 that were contained in the Perinatal Data Registry of Perinatal Services British Columbia. Chi-square tests were conducted to compare maternal sociodemographic characteristics by cannabis use. Logistic regression was conducted to determine the association between cannabis use and SGA and spontaneous preterm births. Cox proportional hazards regression modelling was used to identify the association between cannabis use and stillbirth. Secondary analyses were conducted to ascertain differences by timing of stillbirth (Canadian Task Force Classification II-2).


      Maternal cannabis use has increased in British Columbia over the past decade. Pregnant women who use cannabis are younger and more likely to use alcohol, tobacco, and illicit substances and to have a history of mental illness. Using cannabis in pregnancy was associated with a 47% increased risk of SGA (adjusted OR 1.47; 95% CI 1.33–1.61), a 27% increased risk of spontaneous preterm birth (adjusted OR 1.27; 95% CI 1.14–1.42), and a 184% increased risk of intrapartum stillbirth (adjusted HR [aHR] 2.84; 95% CI 1.18–6.82). The association between cannabis use in pregnancy and overall stillbirth and antepartum stillbirth did not reach statistical significance, but it had comparable point estimates to other outcomes (aHR 1.38; 95% CI 0.95–1.99 and aHR 1.34; 95% CI 0.88–2.06, respectively).


      Cannabis use in pregnancy is associated with SGA, spontaneous preterm birth, and intrapartum stillbirth.



      Cette étude visait à déterminer s'il y a une association entre la consommation de cannabis pendant la grossesse et la mortinaissance, la petite taille pour l’âge gestationnel (< 10e centile) et la naissance prématurée spontanée (< 37 semaines).


      Nous nous sommes servis de données obstétricales et néonatales extraites des dossiers médicaux de femmes ayant accouché en Colombie-Britannique entre le 1er avril 2008 et le 31 mars 2016. Les données sont tirées du Perinatal Data Registry des services périnataux de la Colombie-Britannique. Un test du chi carré a été effectué pour comparer les caractéristiques sociodémographiques des mères selon leur consommation de cannabis, et une régression logistique a servi à déterminer s'il y avait une association entre la consommation de cannabis et la petite taille pour l’âge gestationnel ou la naissance prématurée spontanée. Un modèle de régression de Cox a été utilisé pour établir une association entre la consommation de cannabis et la mortinaissance. Des analyses secondaires ont été effectuées pour évaluer les différences en fonction du moment de la mortinaissance (classification II-2 du Groupe d’étude canadien).


      Au cours des 10 dernières années, la consommation de cannabis pendant la grossesse a augmenté en Colombie-Britannique. Les femmes enceintes qui consomment du cannabis sont plus jeunes qu'avant et sont plus susceptibles de consommer de l'alcool, du tabac et des substances illicites ou d'avoir des antécédents de troubles de santé mentale. La consommation de cannabis pendant la grossesse a été associée à un risque accru de petite taille pour l’âge gestationnel de l'ordre de 47 % (RC ajusté : 1,47; IC à 95 % : 1,33–1,61), à un risque accru de naissance prématurée spontanée de l'ordre de 27 % (RC ajusté : 1,27; IC à 95 % : 1,14–1,42) et à un risque accru de mortinaissance intrapartum de l'ordre de 184 % (RR ajusté [RRA] : 2,84; IC à 95 % : 1,18–6,82). Ni l'association entre la consommation de cannabis pendant la grossesse et le taux global de mortinaissances, ni celle entre la consommation pendant la grossesse et la mortinaissance antepartum n’étaient significatives, mais leurs estimations ponctuelles étaient comparables à celles des autres issues (RRA : 1,38; IC à 95 % : 0,95–1,99; et RRA : 1,34; IC à 95 % : 0,88–2,06, respectivement).


      La consommation de cannabis pendant la grossesse est associée à une petite taille pour l’âge gestationnel, à la naissance prématurée spontanée et à la mortinaissance intrapartum.

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