A systematic review of 46 studies found prenatal co-exposure to cannabis and tobacco was associated with additive or synergistic harms to offspring physical development, emotional regulation, and physiological outcomes beyond single-substance exposure.
Obstetricians, prenatal health providers, substance use cessation counselors
Additive/synergistic harms beyond single-substance exposure
What the researchers found
Among 46 studies (43 human, 3 preclinical), co-exposed infants showed higher risk of compromised physical development and birth defects compared to single-substance exposure. Behavioral outcomes, particularly emotion regulation/reactivity, and physiological outcomes showed similar patterns of worse outcomes with co-exposure. However, other neonatal outcomes (preterm birth, respiratory distress) and cognition were similar between co-exposure and single-substance groups.
Why it matters
Cannabis and tobacco co-use during pregnancy is common, yet most research examines each substance in isolation. This review provides the first comprehensive synthesis showing that co-exposure produces harms beyond what either substance alone would cause, information critical for prenatal counseling.
The numbers in context
46 studies included (43 human, 3 preclinical); 3,217 records screened; co-exposure associated with worse physical development, birth defects, and emotional regulation compared to single-substance exposure; preterm birth and cognition similar between groups
How the study worked
Systematic review searching Medline, Embase, and PsycINFO via OVID. Included human and animal studies comparing prenatal co-exposure to cannabis and nicotine/tobacco with single-substance exposure on neonatal, behavioral, cognitive, and physiological outcomes. 46 of 3,217 identified records met inclusion criteria.
What this study cannot tell us
Included studies varied widely in methodology, sample sizes, and outcome measures. Difficulty separating effects of co-use from effects of heavier overall substance use. Self-reported prenatal substance use likely underestimates true exposure. Limited preclinical evidence (only 3 animal studies).
How to read the evidence
Systematic review with comprehensive search strategy provides moderate evidence, though heterogeneity of included studies and reliance on self-reported exposure limit confidence.
When this study was published
2025 publication
The bigger picture
As prenatal cannabis use rises while tobacco use declines, the substantial population of women who use both substances may face compounded risks that are missed when each substance is studied alone. Clinical guidelines need to address co-use explicitly.
Questions still open
- What are the mechanisms behind additive/synergistic effects of co-exposure? Would cessation of one substance during pregnancy significantly reduce co-exposure harms?
Common questions
Is using both cannabis and tobacco during pregnancy worse than using just one?
Were all outcomes worse with co-exposure?
Read the original research
A systematic review investigating prenatal cannabis and tobacco co-exposure: Impacts on neonatal, behavioral, cognitive and physiological outcomes.
Drug and alcohol dependence reports, 17, 100376
Citation
Argote, Mathilde; Hilson, Leah; Sorkhou, Maryam; Rabin, Rachel A. (2025). A systematic review investigating prenatal cannabis and tobacco co-exposure: Impacts on neonatal, behavioral, cognitive and physiological outcomes.. Drug and alcohol dependence reports, 17, 100376. https://doi.org/10.1016/j.dadr.2025.100376
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