Both THC and CBD cross the placenta and can affect the fetus directly, but cannabinoid receptors throughout the placenta mean these substances can also impair placental development and function, contributing to growth restriction and other adverse outcomes.
Obstetricians, maternal-fetal medicine specialists, pregnant cannabis users, reproductive researchers.
Both THC and CBD cross the placenta and affect placental receptor signaling
What the researchers found
Cannabinoid receptors are expressed throughout the human and murine placenta. Both THC and CBD cross the placenta. Prenatal cannabinoid exposure is linked to small for gestational age and fetal growth restriction. Studies including placental analysis identified changes in placental vasculature and function. In vitro studies show cannabinoid effects on cell proliferation, angiogenesis, and migration in placental cells.
Why it matters
Cannabis use during pregnancy is increasing as pregnant women use it for morning sickness and anxiety. This review highlights that the risk is not just from direct fetal exposure but also from cannabis disrupting the placenta itself, which could impair nutrient delivery and fetal growth.
The numbers in context
Cannabis concentrations have increased dramatically over 20 years. Cannabinoid receptors found throughout placenta. Prenatal exposure linked to growth restriction. Placental vasculature and function changes documented in exposed pregnancies.
How the study worked
Narrative review summarizing clinical, animal model, and in vitro evidence on how phytocannabinoids affect placental development and function, with focus on receptor distribution and signaling pathways.
What this study cannot tell us
Narrative review without systematic methodology. Much evidence is from in vitro or animal models. Clinical studies with placental analysis are few. Cannabis product composition varies widely. Timing and dose of exposure likely matter but are poorly characterized.
How to read the evidence
Narrative review integrating clinical, animal, and in vitro evidence. Mechanistic plausibility is strong but clinical evidence is limited.
When this study was published
Published in 2023.
The bigger picture
Most prenatal cannabis research focuses on the developing brain, but the placenta is the first point of contact. If cannabinoids impair placental blood vessel development or nutrient transport, the downstream effects on the fetus could extend well beyond direct cannabinoid exposure.
Questions still open
- At which gestational stage is the placenta most vulnerable to cannabinoid disruption?
- Do different cannabinoids (THC vs. CBD vs. isolated compounds) have different placental effects?
Common questions
Does cannabis affect the placenta?
Is CBD safe during pregnancy?
Read the original research
Cannabinoids and the placenta: Receptors, signaling and outcomes.
Placenta, 135, 51-61
Citation
Rokeby, Abbey C E; Natale, Bryony V; Natale, David R C. (2023). Cannabinoids and the placenta: Receptors, signaling and outcomes.. Placenta, 135, 51-61. https://doi.org/10.1016/j.placenta.2023.03.002
Explore the wider topic
- How to Talk to Your Teenager About Weed (Without Losing Them)
- My Kid's Friends Smoke Weed: A Parent's Guide
- I Smoke Weed But Don't Want My Kids To: Navigating the Hypocrisy
- Quitting Weed as a Parent: Why It Is the Hardest and Most Important Quit
- Quitting Weed as a Teen or Young Adult
- My Kid Is Smoking Weed: A Parent's Guide