Cannabis Use During Pregnancy Is Associated with the Suppression of Circulating Maternal Cytokines

The prevalence of prenatal cannabis use has nearly doubled in the United States. Cannabinoid 2 receptors are predominately expressed in cells of the human immune system, and delta-9 tetrahydrocannabinol (THC), the primary active component of cannabis, has been shown to suppress immune responses. Despite these findings, there is very little evidence on the impact of cannabis use on maternal immune system. Here, we evaluate the association between urine-verified cannabis use and the levels of T helper cytokines in the maternal circulation.

This was an ancillary study of a prospective cohort of pregnant women who participated in the Michigan Archive for Research on Child Health study. Pregnant women (age ≥18 years) were recruited from 22 prenatal clinics in Michigan and matched on age, race, and tobacco smoking (n = 144). The urinary metabolite of delta-9 THC, 11-nor-9-carboxy-delta-9-THC (THC-COOH), was used to define cannabis use status. A bead-based assay was used for the simultaneous detection of maternal cytokines associated with cannabis use and pregnancy outcomes in previous studies.

Repeated-measures linear mixed models indicated that urine-verified cannabis use was associated with the suppression of maternal pro-inflammatory cytokines including interferon gamma (β = -0.5; 95% confidence interval [CI] = -0.8, -0.1) and interleukin (IL)-12 (β = -0.3; 95% CI = -0.6, -0.05), as well as the anti-inflammatory IL-4 (β = -0.7; 95% CI = -1.3, -0.2) and IL-10 (β = -0.4; 95% CI = -0.7, -0.03). Similar results were observed when heavy cannabis use was defined using the top tertile of urinary THC-COOH at each trimester.

Urine-verified cannabis use was associated with the suppression of pro- and anti-inflammatory T helper cytokines in a cohort of pregnant women, suggesting that cannabis use can lead to modest dysregulation of the maternal immune system. Additional studies are needed to investigate the role of maternal immune responses in explaining birth outcomes linked to cannabis use.