A Review of How THC and CBD Cross the Placenta and May Affect Fetal Development Through Placental Receptors

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.

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.

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.

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.

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.