Combined cannabis and nicotine use in pregnancy linked with adverse perinatal outcomes

By Melanie Hinze

Combined use of cannabis and nicotine during pregnancy is linked with increased neonatal and infant death and increased maternal and neonatal morbidity compared with use of either substance alone, according to US research published in JAMA Network Open.

The retrospective population-based cohort study used linked hospital discharge data and vital statistics for just over 3 million pregnant individuals (mean age, 29.3±6 years) with singleton gestations and gestational ages of 23 to 42 weeks. Participants were grouped into four categories: cannabis users (0.7% of the cohort), nicotine users (1.8%), combined cannabis and nicotine users (0.3%) and a control group who had no cannabis or nicotine use (97.1%). The main outcomes measured were infant and neonatal deaths, infants small for gestational age and preterm delivery.

When compared with nonusers, those who used cannabis or nicotine had increased rates of infant death (0.7% for both cannabis and nicotine use), neonatal death (0.3% for both), small for gestational age (14.3% and 13.7%, respectively) and preterm delivery (12.2% and 12.0%, respectively).

In those who used both cannabis and nicotine, risks were higher for infant death (1.2%), neonatal death (0.6%), small for gestational age (18.0%) and preterm delivery (17.5%).

Compared with nonusers, users of both cannabis and nicotine were more likely to be white and to have fewer than five prenatal visits during the course of their pregnancy. They were also more likely to have a mental health disorder, chronic hypertension and pre-existing diabetes compared with the control group.

‘Given the increasing prevalence of combined cannabis and nicotine use in pregnancy, these findings can help guide health care practitioners with preconception and prenatal counselling, especially regarding the benefits of cessation,’ the study authors wrote.

Professor Michael Farrell, Director of the National Drug and Alcohol Research Centre, UNSW Medicine, UNSW Sydney, said this was an interesting study in which the combination of cannabis and tobacco use was associated with higher rates of neonatal morbidity.

‘There may be complex social and demographic confounders, but in the era of cannabis legalisation this is an important public health finding,’ he said.

JAMA Netw Open 2024; 7(5): e2410151.