Adding Marijuana to Tobacco During Pregnancy Did Not Worsen Birth Outcomes

There were no significant differences in any birth outcome (APGAR scores, respiratory distress, NICU admission, growth restriction, birth weight, length, head circumference, gestational age, hospital stay) between tobacco-only users (n=71) and tobacco-plus-marijuana users (n=127). However, rates of adverse outcomes were high in both groups compared to expected rates in unexposed pregnancies.

Retrospective chart review of pregnant women identified via self-report or biochemical testing who used tobacco alone (n=71) or tobacco and marijuana simultaneously (n=127) at any point during pregnancy. Outcomes compared using linear regression and odds ratio analysis.

Many pregnant women who use tobacco also use marijuana. This study suggests that in the context of tobacco use, marijuana does not add measurable risk, implying that tobacco may be the primary driver of the adverse birth outcomes seen in polysubstance-using pregnancies.

This finding is consistent with the earlier study (RTHC-05710) showing cannabis co-exposure did not worsen tobacco's cognitive effects on children. The pattern suggests tobacco's effects may dominate the prenatal harm picture when both are used.

Small sample sizes limit statistical power to detect small differences. Retrospective design with chart review. Self-report and biochemical testing may not capture all exposure. No unexposed comparison group. Cannot determine dose, frequency, or timing of either substance.