Increased discussion around cannabis (weed or marijuana) has raised questions about its safety during pregnancy. This article explores scientific evidence and expert recommendations on cannabis use during this time. Understanding potential effects on both the pregnant individual and developing baby is crucial for informed health decisions.
How Cannabis Affects Fetal Development
Delta-9-tetrahydrocannabinol (THC), cannabis’s main psychoactive component, readily crosses the placenta, directly exposing the developing fetus. Cannabinoid receptors are present in the fetal brain and placenta, suggesting that THC can interfere with normal developmental processes. Studies in animal models have shown that regular exposure to low-dose THC, mimicking daily use, can reduce birth weight by approximately eight percent and decrease brain and liver growth by over 20 percent.
Prenatal cannabis exposure has been associated with a higher risk of adverse birth outcomes, including lower birth weight and prematurity. Some research indicates cannabis use can lead to fetal growth restriction. Additionally, THC can alter the placental and fetal epigenome, affecting gene regulation and expression in key areas like the placenta, fetal lung, brain, and heart. These epigenetic changes may be consistent with those seen in neurobehavioral conditions.
Some studies suggest a potential link between prenatal cannabis exposure and certain birth defects, though evidence is often mixed. Specific anomalies reported include gastroschisis (intestines outside abdomen at birth) or Epstein’s anomaly (a heart valve condition). Animal studies have shown that THC can cause birth defects in genetically predisposed mice, particularly affecting brain and face development, highlighting a potential environmental risk factor.
Maternal Health Considerations
Some pregnant individuals consider cannabis for morning sickness, but health organizations do not recommend this. Evidence suggests cannabis is not an effective treatment for nausea and vomiting in pregnancy and may even worsen symptoms. Cannabis products also have a greater side effect profile compared to alternative treatments with established safety data.
Maternal cannabis use can also pose other health risks during pregnancy. There may be an increased risk of anemia (a condition where the body lacks healthy red blood cells). Smoking cannabis also exposes the pregnant person and fetus to carbon monoxide, up to five times higher than with cigarettes. This reduces oxygen in the bloodstream, potentially affecting the baby’s brain development and increasing the mother’s breathing problems.
Impact on the Child’s Post-Natal Development
Exposure to cannabis in the womb can have lasting effects on a child’s cognitive and behavioral development, often apparent after birth and continuing into adolescence. Children exposed prenatally to cannabis have shown lower scores on tests of visual problem-solving, visual-motor coordination, and attention span. They may also experience memory issues, learning difficulties, and impaired executive function (skills like attention, memory, and problem-solving).
Research indicates an association between prenatal cannabis exposure and behavioral challenges like hyperactivity, inattention, and increased aggression. These effects can persist into early adolescence, potentially increasing the risk of mental health disorders and later substance use. Studies have also linked prenatal THC exposure to sleep disorders in children, including difficulties initiating and maintaining sleep.
Official Health Organization Guidance
Major health organizations advise against cannabis use in any form during pregnancy and while breastfeeding due to potential harms to the fetus and child. The American College of Obstetricians and Gynecologists (ACOG), the Centers for Disease Control and Prevention (CDC), and the American Academy of Pediatrics (AAP) consistently recommend that pregnant individuals abstain from cannabis.
There is no known safe amount of cannabis use during pregnancy or lactation. This recommendation applies to all consumption methods, including smoking, vaping, edibles, and oils. Health organizations emphasize that current findings are concerning enough to warrant complete avoidance. Medical professionals are advised to counsel patients about these risks and encourage alternative therapies with better safety profiles for pregnancy.