Marijuana is one of the most widely used drugs globally. Rising legalization has fueled greater social acceptance and lowered perceptions of risk even as research continues to highlight its harms. A recent study published in Pediatric Research reviewed years of evidence from both animal models and human studies, examining how marijuana impacts pregnant women and their babies.

How marijuana affects the body during pregnancy

One of the critical human body systems is the Endocannabinoid System (ECS), which helps regulate memory, appetite, emotions, and even fetal development. During pregnancy, the ECS is especially active, influencing hormonal signaling, fetus brain development, and placental development.

When marijuana is used, cannabinoids such as THC enter and interfere with the ECS, disrupting its natural processes. Because THC is lipophilic, meaning it binds strongly to fat, THC crosses into fatty tissues and can be stored there for weeks. This is especially concerning during pregnancy because the membrane of the placenta, which is the critical organ that supplies the developing baby with nutrients and oxygen, is mostly made of fatty molecules enabling THC to enter with ease. About one-third of the THC in the mother’s body reaches the fetus and once there, it can accumulate in the developing brain and other fatty tissues. Animal studies show that even after marijuana use stops, the developing fetus continues to be exposed to THC, potentially altering how organs and systems grow.

Long term effects extend beyond infancy

Research finds that marijuana use during pregnancy is associated with:

  1. Fetal growth problems: Babies exposed to marijuana in the womb are more likely to be born small for their gestational age, be admitted to the NICU, and face a 75% increased risk of low birth weight. Even short-term exposure during early pregnancy can impact fetal growth.
  2. Developmental delays: Long-term studies show that marijuana-exposed children may struggle with memory, attention, problem-solving, and emotional regulation.
  3. Higher risk of metabolic and heart problems: Prenatal marijuana exposure may change how the body processes insulin and stores fat which could increase the risk of obesity, diabetes, and heart disease later in life.
  4. Increased vulnerability to addiction: Prenatal marijuana exposure changes the brain pathways involved in reward and impulse control which may increase the risk of substance use and mental health challenges during adolescence and adulthood.

In some studies, girls’ exposure to marijuana in the womb showed more behavioral problems including aggression and attention issues, as early as 18 months of age.

With the marijuana industry falsely promoting products as “natural,” safe remedies for various health conditions, and alternatives to other substances, it is critical that women of childbearing age understand that marijuana use is not risk-free. Research consistently shows that marijuana can affect fetal development, leading to long-lasting consequences for a child’s physical and mental health.

For science-based resources on marijuana use during pregnancy, as well as tools for parents and fathers, visit https://www.marijuanaknowthetruth.org/marijuana-and-pregnancy/. If you are in Florida, our grant program allows us to provide and distribute these resources to you free of charge. Complete this request form to access materials ranging from Go-to-Guides to Fast Facts for Fathers.

Prevention starts with education, and staying informed can help protect future generations.

Sources

Krishnan, P., & Yen, E. (2025). The changing landscape of cannabis use: impact on maternal health and neonatal outcomes. Pediatric research, 10.1038/s41390-025-04209-4. Advance online publication. https://doi.org/10.1038/s41390-025-04209-4

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