Early Maternal Prenatal Cannabis Use and Child Developmental Delays

IMPORTANCE Maternal prenatal cannabis use is associated with adverse neonatal health effects, yet little is known about its association with child developmental outcomes. OBJECTIVE To evaluate associations between maternal prenatal cannabis use in early pregnancy and child early developmental delays. DESIGN, SETTING, AND PARTICIPANTS This cohort study included 119 976 children born to 106 240 unique individuals between January 2015 and December 2019 and followed up to aged 5.5 years or younger (through December 31, 2021) at Kaiser Permanente Northern California. Individuals were screened for prenatal cannabis use via self-report and urine toxicology at entrance into prenatal care (approximately 8- to 10-weeks' gestation). Data were analyzed from February 2023 to March 2024. EXPOSURE Maternal prenatal cannabis use defined as any use (self-reported or by urine toxicology testing) and use frequency. Main OutcomesEarly developmental delays (speech and language disorders, motor delays, global delays) in children up to age 5.5 years defined by International Statistical Classification of Diseases and Related Health Problems, Ninth Revision and Tenth Revision diagnoses codes ascertained from electronic health records. RESULTS In this cohort of 119 976 pregnancies among 106 240 unique pregnant individuals, there were 29 543 Hispanic pregnancies (24.6%), 6567 non-Hispanic Black pregnancies (5.5%), 46 823 non-Hispanic White pregnancies (39.0%), 12 837 pregnancies (10.7%) to individuals aged 24 years or younger, and 10 365 pregnancies (8.6%) to individuals insured by Medicaid. Maternal prenatal cannabis use was documented for 6778 pregnancies (5.6%). Daily maternal prenatal cannabis use was reported for 618 pregnancies (0.5%), weekly for 722 pregnancies (0.6%), and monthly or less for 1617 pregnancies (1.3%). No association was observed between maternal prenatal cannabis use and child speech and language disorders (HR, 0.93; 95% CI, 0.84-1.03), global developmental delays (HR, 1.04; 95% CI, 0.68-1.59), or motor delays (HR, 0.86; 95% CI, 0.69-1.06). No association was detected between the frequency of maternal prenatal cannabis use and child early developmental delays. CONCLUSION AND RELEVANCE In this cohort study, maternal prenatal cannabis use was not associated with an increased risk of child early developmental delays. Future research is needed to assess different patterns of cannabis use throughout pregnancy. Given the association between maternal prenatal cannabis use and other adverse outcomes, pregnant individuals should be educated on those risks.