Cannabis Use in Pregnancy Is Associated With an Increased Incidence of Low Birth Weight and Small-for-Gestational-Age Infants

Is cannabis use in pregnancy associated with adverse neonatal outcomes?

Cannabis use in pregnancy is associated with low birth weight (LBW) and small-for-gestational-age (SGA) infants with a dose-response gradient. There are probable small associations with preterm birth or neonatal intensive care unit admission. This information may be useful in counseling patients who are pregnant, especially now that recreational use has been legalized in many states. We can expect that there will be further, mostly observational, studies on this topic. (Level of Evidence = 2b)

The authors report the findings of a retrospective cohort study from the Kaiser Permanente–Northern California integrated health care delivery system, including commercial, Medicare, and Medicaid plans. The study included infants of singleton pregnancies (N = 364,924) born 2011 to 2020 with Kaiser Permanente–Northern California health plan coverage at some point in the pregnancy, at least one prenatal visit, and an affirmative maternal response to a questionnaire about cannabis use or a urine toxicology test result positive for cannabis (done as a routine prenatal laboratory test).

The choices for self-reported cannabis use were never, monthly or less, weekly, daily, or unknown frequency with positive toxicology. Covariates included demographic information, noncannabis in utero substance exposure (eg, alcohol, opioids, stimulants, anxiolytic/sleep medications), adequacy of prenatal care, maternal comorbidities, and antidepressant medication use. Cannabis use was identified in 22,624 women (6.2%), and 9,578 of those were identified by self-report. LBW and SGA in infants were associated with cannabis use in unadjusted and adjusted models (LBW: adjusted odds ratio = 1.20; 95% CI, 1.12–1.28; SGA: adjusted odds ratio = 1.24; 95% CI, 1.18–1.30). Dose-response analyses showed a significant trend related to reported use in both cases (P < .001). Preterm birth and neonatal intensive care unit admissions were not significantly associated with cannabis use in the fully adjusted model.

Study design: Cohort (retrospective)

Funding source: Government

Setting: Population-based

Reference: Avalos LA, Adams SR, Alexeeff SE, et al. Neonatal outcomes associated with in utero cannabis exposure: a population-based retrospective cohort. Am J Obstet Gynecol. 2024;231(1):132.e1-132.e13.