The general medical consensus strongly discourages using cannabis, whether by smoking, vaping, or consuming edibles, throughout pregnancy and while breastfeeding. Cannabis contains compounds like delta-9-tetrahydrocannabinol (THC), the psychoactive agent, and cannabidiol (CBD). These substances pose potential risks to the developing fetus. Scientific evidence indicates that exposure to these compounds can disrupt fundamental biological processes in the womb. This article explains how cannabis affects the fetus, outlining the documented risks and current public health guidance.
How Cannabis Compounds Reach the Fetus
The primary concern with cannabis use during pregnancy is the transfer of its active components from the mother’s bloodstream to the developing fetus. Tetrahydrocannabinol (THC), a highly lipophilic, or fat-soluble, molecule, easily navigates the maternal-fetal barrier, crossing the placenta and entering the fetal circulation. Once in the fetal system, THC can bind to cannabinoid receptors in the same way the body’s own naturally produced cannabinoids do.
The endocannabinoid system (ECS) is present from the earliest stages of development, playing a role in embryo implantation and placenta formation. The ECS is also deeply involved in fetal brain development, guiding processes like neuron migration, synapse formation, and the differentiation of neural progenitor cells. Introducing external cannabinoids like THC disrupts this finely tuned signaling system, which can alter the timing and organization of the developing nervous system.
When cannabis is consumed through smoking or vaping, combustion byproducts compound the exposure risk. Cannabis smoke, similar to tobacco smoke, contains carbon monoxide, which is readily absorbed into the mother’s blood. Carbon monoxide passes to the fetus, reducing the blood’s oxygen-carrying capacity and potentially leading to fetal hypoxia. This reduction in oxygen availability can impair fetal growth and development, adding a physical risk separate from the chemical effects of the cannabinoids.
Documented Risks to Fetal Development
Prenatal exposure to cannabis is consistently associated with several adverse outcomes concerning physical development. One documented risk is fetal growth restriction, resulting in lower birth weight and smaller-for-gestational-age infants. Exposure is also linked to a greater likelihood of preterm birth (delivery before 37 weeks of gestation), a condition carrying significant health challenges for the newborn.
Babies exposed to cannabis in utero also face a higher chance of requiring admission to the neonatal intensive care unit (NICU). The risks extend beyond immediate birth outcomes, as THC’s interference with the developing brain has been shown to have lasting effects on neurodevelopment. The developing central nervous system is highly sensitive to the disruption of the endocannabinoid signaling that is integral to its formation.
Children exposed to cannabis prenatally demonstrate altered behavioral and cognitive patterns later in childhood. Studies show a connection between prenatal cannabis use and difficulties with attention, memory, and impulse control. These neurodevelopmental consequences can manifest as hyperactivity and impaired executive function, affecting a child’s ability to plan, focus, and manage multiple tasks. Since the long-term impacts are still being investigated, and modern cannabis products often contain higher THC concentrations, scientific understanding supports a strong cautionary approach.
Medical and Public Health Guidance
Leading health organizations in the United States maintain a unified stance advising against any cannabis use during the preconception period, pregnancy, and lactation. The American College of Obstetricians and Gynecologists (ACOG) and the American Academy of Pediatrics (AAP) both recommend complete abstinence due to the uncertain and potentially harmful effects on the fetus and newborn. These recommendations apply to all forms of cannabis, including products containing CBD, edibles, and those used for medical purposes.
The Centers for Disease Control and Prevention (CDC) echoes this guidance, discouraging the use of marijuana throughout pregnancy. Professional bodies emphasize that no amount of cannabis has been proven safe for use during pregnancy, and no medical indication outweighs the potential risks to the fetus. Health organizations urge obstetric providers to screen all patients for cannabis use in a non-judgmental, universal manner at the first prenatal visit and throughout the pregnancy.
Counseling should focus on educating patients about how THC and other cannabinoids cross the placenta and the potential for adverse outcomes, such as low birth weight and neurodevelopmental changes. Individuals using cannabis to manage medical conditions like nausea or pain should discontinue use and be offered alternative therapies with established safety profiles for pregnancy. This universal recommendation stands regardless of the legal status of cannabis in a patient’s state.
Resources for Quitting During Pregnancy
For individuals seeking to stop using cannabis during pregnancy, the initial step is to speak openly with an obstetrician, midwife, or other healthcare provider. These professionals can offer non-judgmental support and connect patients with specialized resources designed for pregnant individuals. Honest communication allows the healthcare team to find safer, alternative ways to manage symptoms like nausea or anxiety, which are often cited reasons for cannabis use during pregnancy.
Behavioral therapies are considered the most effective form of treatment for cannabis use disorder, particularly during pregnancy. Cognitive Behavioral Therapy (CBT) is one widely used approach that helps individuals recognize triggers and develop coping strategies to manage cravings and avoid relapse. Motivational interviewing is another supportive technique often employed by clinicians to strengthen a person’s motivation for change.
National resources offer confidential and immediate support for individuals needing help with substance use. The Substance Abuse and Mental Health Services Administration (SAMHSA) operates a National Helpline that provides free, confidential, 24/7 information and referrals to local treatment facilities. Additionally, peer-support programs such as Marijuana Anonymous (MA) offer a non-clinical environment where individuals can connect with others who have successfully stopped using cannabis.