Prenatal Cannabis Exposure Linked to Possible Communication Delays at 12 Months, But Finding Did Not Survive Statistical Correction

Prenatal cannabis exposure was not associated with differences in gestational age or birth weight. It was significantly associated with increased risk of parent-reported developmental delay on the communication domain (p = .02), but this finding did not survive correction for multiple comparisons. No other ASQ-3 domains showed significant associations.

Prospective cohort from the Pregnancy During the COVID-19 Pandemic study (n = 10,695 total; n = 3,742 with 12-month ASQ-3 assessments). Propensity score weighting addressed demographic differences between cannabis-using and non-using groups. G-computations analyzed associations with birth outcomes and developmental delay.

Cannabis use during pregnancy is increasing with legalization, and the developmental consequences remain unclear. This large study found limited evidence of harm at 12 months, with only a borderline signal for communication development that warrants monitoring but does not establish clear risk.

The question of prenatal cannabis safety is one of the most important and unsettled in perinatal research. This study joins a growing literature showing mixed results, with some subtle signals in communication and language development that may emerge more clearly at later ages when language demands increase.

The study was not specifically designed to examine prenatal cannabis effects. Cannabis use was self-reported and may be underreported. The ASQ-3 is a parent-report screening tool, not a comprehensive developmental assessment. Follow-up at 12 months may be too early to detect some developmental effects. The COVID-19 pandemic context may introduce unique confounders.