Advancing a Pre-Clinical Model of Full-Term Prenatal Exposure to Vaporized Δ9-Tetrahydrocannabinol.

Jenkins B.; Moore C.; Tiwari P.; Lichtman A.; Poklis J.; Jantzie L.; Weerts E. · Cannabis and cannabinoid research · 2026

**Background & Methods** This preclinical study developed and characterized a novel rat model of full-term prenatal cannabinoid exposure (PCE) using vaporized THC. Pregnant Sprague-Dawley rats were exposed to THC vapor (200 mg/mL, n=13) or vehicle control (n=8) daily throughout gestation until postnatal day 10, with blood and brain tissue sampling at gestational day 20 and postnatal day 10 to quantify THC and metabolite concentrations. **Key Findings** • THC vapor exposure during pregnancy reduced maternal food intake and shortened total gestation days compared to controls, though offspring birth weights were not significantly different; however, postnatal weights were decreased in THC-exposed pups. • THC and its metabolites (11-OH-THC and THCCOOH) readily crossed the placental barrier and accumulated in fetal brains. On gestational day 20, fetal brain concentrations of THC, 11-OH-THC, and THCCOOH were 12%, 118%, and 75% of maternal plasma levels, respectively. • Postnatal day 10 pups demonstrated persistent high brain THC (29.6 ± 8.5 ng/g) and 11-OH-THC (9.8 ± 2.1 ng/g) concentrations, with THCCOOH undetectable, indicating active brain accumulation and metabolic processing of THC in developing offspring. **Dosage & Administration** THC vapor exposure: 200 mg/mL concentration administered via inhalation daily throughout gestation (approximately human-equivalent full-term period) through postnatal day 10. Vehicle control: 100% propylene glycol vapor. **Safety & Adverse Effects** Maternal adverse effects included decreased food intake and shortened gestation period. Offspring demonstrated reduced postnatal weight gain. No other acute adverse effects were specifically reported in this preclinical model. **Evidence Quality** This is a preclinical animal study with significant limitations for human translation. The small sample size (n=13-8 per group), use of a single rat strain, and vapor exposure methodology may not fully replicate human cannabis vaping patterns. The study lacks long-term developmental and behavioral outcome data, which the authors identify as future research directions. As a model development paper, findings provide methodological foundation for subsequent mechanistic studies but cannot directly inform clinical outcomes in human pregnancies. Evidence quality is moderate for establishing feasibility of the model but insufficient for clinical recommendations.

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