Prenatal THC Exposure Linked to Smaller Babies Who Then Grow Rapidly
Babies exposed to THC in the womb had less body fat at birth but then grew rapidly, with breastfeeding potentially stabilizing the growth pattern.
Quick Facts
What This Study Found
Among 128 mother-child pairs, prenatal THC exposure (12% of children) was associated with 95g less fat mass and 2.1% lower adiposity at birth, followed by rapid postnatal growth (0.42 BMI z-score increase per square root year). Shorter breastfeeding duration amplified this pattern, with 1.1 higher BMI z-score by age 3.
Key Numbers
128 pairs, 15 (12%) THC-exposed, 3 with concurrent CBD. THC associated with -95g fat mass (95% CI: -174 to -14), -2.1% adiposity (CI: -4.2 to -0.4). Rapid growth: +0.42 BMI z-score/sqrt year. Short breastfeeding: +1.1 BMI z-score at age 3.
How They Did This
Prospective cohort following 128 mother-child pairs through 3 years, with mid-gestation urinary THC and CBD measurement, neonatal body composition assessment, and longitudinal BMI tracking.
Why This Research Matters
The pattern of being born small then growing rapidly is associated with metabolic problems later in life. This study identifies a specific cannabinoid-driven growth trajectory that could have long-term health consequences.
The Bigger Picture
Born-small-then-grow-fast is a well-known risk pattern for later obesity and metabolic syndrome. If prenatal THC creates this trajectory, it has implications for the growing number of pregnancies with cannabis exposure.
What This Study Doesn't Tell Us
Small sample with only 15 THC-exposed children limits statistical power. Urinary measurement captures recent use rather than cumulative exposure. Breastfeeding may also transfer THC, complicating the protective finding. Only followed to age 3.
Questions This Raises
- ?Does the rapid growth pattern persist beyond age 3?
- ?Does breastfeeding help by stabilizing growth or is it a proxy for other factors?
- ?Would these children face higher metabolic risk later in life?
Trust & Context
- Key Stat:
- THC-exposed babies had 95g less fat at birth but grew rapidly afterward
- Evidence Grade:
- Prospective design with objective biomarker exposure measurement, but very small exposed group limits statistical confidence.
- Study Age:
- 2025 study with follow-up through age 3.
- Original Title:
- Impact of prenatal exposure to delta 9-tetrahydrocannabinol and cannabidiol on birth size and postnatal growth trajectories.
- Published In:
- Pediatric obesity, 20(1), e13187 (2025)
- Authors:
- Moore, Brianna F(4), Mueller, Noel T, Perng, Wei, Sauder, Katherine A, Hébert, Emily T, Hoyt, Adrienne T, Wymore, Erica M, Boyle, Kristen E, Su, Emily J, Shapiro, Allison L B, Kinney, Gregory, Sempio, Cristina, Klawitter, Jost, Christians, Uwe, Dabelea, Dana
- Database ID:
- RTHC-07180
Evidence Hierarchy
Enrolls participants and follows them forward in time.
What do these levels mean? →Frequently Asked Questions
Does using cannabis during pregnancy affect the baby's growth?
This study found THC-exposed babies had less body fat at birth but then grew rapidly in the first three years. This born-small-then-grow-fast pattern is associated with metabolic health risks later in life.
Does breastfeeding help THC-exposed babies?
Breastfeeding appeared to stabilize growth patterns in THC-exposed infants. However, since breast milk can also contain THC, the researchers note that the impact of lactational exposure needs further investigation.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-07180APA
Moore, Brianna F; Mueller, Noel T; Perng, Wei; Sauder, Katherine A; Hébert, Emily T; Hoyt, Adrienne T; Wymore, Erica M; Boyle, Kristen E; Su, Emily J; Shapiro, Allison L B; Kinney, Gregory; Sempio, Cristina; Klawitter, Jost; Christians, Uwe; Dabelea, Dana. (2025). Impact of prenatal exposure to delta 9-tetrahydrocannabinol and cannabidiol on birth size and postnatal growth trajectories.. Pediatric obesity, 20(1), e13187. https://doi.org/10.1111/ijpo.13187
MLA
Moore, Brianna F, et al. "Impact of prenatal exposure to delta 9-tetrahydrocannabinol and cannabidiol on birth size and postnatal growth trajectories.." Pediatric obesity, 2025. https://doi.org/10.1111/ijpo.13187
RethinkTHC
RethinkTHC Research Database. "Impact of prenatal exposure to delta 9-tetrahydrocannabinol ..." RTHC-07180. Retrieved from https://rethinkthc.com/research/moore-2025-impact-of-prenatal-exposure
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.