Cannabis and Pregnancy - Research Review

By Avery Martz | Updated August 2026

In my years working in hemp and cannabis, I've encountered pregnant women who use cannabis or are trying to decide whether they should. Research suggests cannabis use during pregnancy has increased alongside greater accessibility and social acceptance. 

At the same time, cannabis advocacy groups increasingly highlight research suggesting prenatal cannabis exposure may not be as dangerous as you might think. We believe that messaging gives an incomplete picture of the evidence and influences how people perceive the risks of cannabis use during pregnancy.

Based on the most robust research available on cannabis and pregnancy, our advice is simple:

Just don't do it.

There are substantial gaps in the research. We are concerned both about the effects of the active chemicals in cannabis itself and the health risks associated with smoking, two sources of risk that have not been adequately disentangled in the research. 

The available evidence does not establish that cannabis use during pregnancy is safe, and there are credible findings that give us reason for concern. In the face of uncertainty and the possibility of serious harm, we defer to the precautionary principle: caution and preventive action are appropriate even when the evidence is incomplete.

There may be circumstances where medical use of cannabis during pregnancy is an option worth considering. This decision should be made with an experienced healthcare provider who can help evaluate the risks in the context of the individual patient. 

We also make an important distinction between the medical use of cannabis and smoking cannabis. We do not ever consider smoking cannabis to be medical use.

Below, we summarize some of the most robust findings on cannabis and pregnancy and explain how they inform our recommendation.

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Related Reading →

• Smoking Is Not a Wellness Strategy (Publishing Soon)
• Is Cannabis Safe During Pregnancy? — How Advocacy Groups Twist the Research

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Pregnancy and Neonatal Outcomes

- Birth Outcomes of Neonates Exposed to Marijuana in Utero: A Systematic Review and Meta-analysis

JAMA Network Open | 2022
Marchand et al.

Findings: This systematic review and meta-analysis included 16 studies and 59,138 patients. Prenatal cannabis exposure was associated with increased risks of low birth weight, small for gestational age, preterm delivery, and NICU admission, as well as modest reductions in mean birth weight, one-minute Apgar scores, and infant head circumference. As with other observational pregnancy research, these associations do not by themselves establish that cannabis caused the outcomes, only that cannabis use is associated with these outcomes.

- The Effects of Cannabis Use During Pregnancy on Low Birth Weight and Preterm Birth: A Systematic Review and Meta-analysis

American Journal of Perinatology | 2024
Baía & Domingues

Findings: This systematic review and meta-analysis included 32 studies and specifically selected studies that attempted to isolate cannabis exposure while controlling for cigarette smoking and other illicit drug use. Cannabis use during pregnancy was associated with increased adjusted odds of low birth weight, preterm birth, and being small for gestational age. The limited evidence examining frequency and timing also suggested greater risk with heavier use and continued use later in pregnancy.

- Cannabis Use in Pregnancy and Neonatal Outcomes: A Systematic Review and Meta-Analysis

Cannabis and Cannabinoid Research | 2024
Lo et al.

Findings: This systematic review included 53 studies. After adjustment for confounding variables, prenatal cannabis use was associated with greater odds of preterm birth, small for gestational age, and perinatal mortality. Adjusted analyses did not find a statistically significant difference in mean birth weight. The authors rated the certainty of evidence as low to very low, reflecting important limitations in the underlying observational research.

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Long-Term Behavioral and Psychiatric Outcomes

- Prenatal Marijuana Exposure, Age of Marijuana Initiation, and the Development of Psychotic Symptoms in Young Adults

Psychological Medicine | 2015
Day et al.

Findings: Researchers followed offspring from pregnancy through age 22. Prenatal marijuana exposure was associated with increased psychotic symptoms in young adulthood after controlling for several potential confounders, including other prenatal substance exposures and the offspring's own substance use. Earlier initiation of marijuana use by the offspring also predicted psychotic symptoms. The observational design cannot establish that prenatal cannabis exposure caused the later symptoms.

 

- Associations Between Prenatal Cannabis Exposure and Childhood Outcomes: Results From the ABCD Study

JAMA Psychiatry | 2021
Paul et al.

Findings: This analysis included 11,489 children ages 9 to 11, including 655 with reported prenatal cannabis exposure. After adjustment for numerous potential confounders, cannabis exposure after maternal knowledge of pregnancy remained associated with greater psychotic-like experiences and externalizing, attention, thought, and social problems. Many other initially observed differences were attenuated after adjustment, illustrating the substantial confounding present in observational research on prenatal cannabis exposure.

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Biological Plausibility and Animal Evidence

- Autoradiographic Study of Pre- and Postnatal Distribution of Cannabinoid Receptors in Human Brain

NeuroImage | 2001
Biegon & Kerman

Findings: Researchers examined CB1 cannabinoid receptor distribution in fetal and adult human brains. CB1 receptors were present in the developing human brain during gestation, with their distribution changing across development. This study does not demonstrate harm from prenatal cannabis exposure. Instead, it provides biological plausibility for concern because THC acts on a signaling system already active during fetal brain development.

- Developmental Consequences of Perinatal Cannabis Exposure: Behavioral and Neuroendocrine Effects in Adult Rodents

Psychopharmacology | 2011
Campolongo et al.

Findings: This review examined experimental studies of cannabinoid exposure during pregnancy and lactation in rodents. Across the reviewed studies, maternal cannabinoid exposure was associated with lasting changes in locomotor activity, cognition, emotional behavior, stress responses, and sensitivity to drugs in adult offspring. Animal findings cannot be directly translated into human risk, but they provide experimental evidence that disrupting cannabinoid signaling during development can produce lasting effects.

- Perinatal Exposure to Delta-9-Tetrahydrocannabinol Causes Enduring Cognitive Deficits Associated With Alteration of Cortical Gene Expression and Neurotransmission in Rats

Addiction Biology | 2007
Campolongo et al.

Findings: Pregnant rats were given THC during late gestation and early lactation at a dose that did not produce overt maternal toxicity. Adult offspring demonstrated lasting cognitive impairment along with alterations in cortical gene expression and glutamatergic and noradrenergic neurotransmission. The experiment provides evidence that developmental THC exposure can cause persistent neurobiological changes in an animal model.

- Bidirectional Cannabinoid Modulation of Social Behavior in Adolescent Rats

Psychopharmacology | 2008
Trezza & Vanderschuren

Findings: Researchers experimentally manipulated cannabinoid signaling in adolescent rats and found that activation and blockade of cannabinoid receptors altered social play behavior. This was not a prenatal cannabis exposure study and does not demonstrate harm from prenatal cannabis exposure. Instead, it provides mechanistic evidence that the endocannabinoid system participates in the regulation of social development and that exogenous manipulation of cannabinoid signaling can alter that process. 

- Delta-9-Tetrahydrocannabinol During Pregnancy in the Rat: II. Effects on Ontogeny of Locomotor Activity and Nipple Attachment in the Offspring

Neurotoxicology and Teratology | 1987
Brake et al.

Findings: Pregnant rats were administered THC during the final two weeks of gestation and their offspring were followed after birth. Prenatal THC exposure altered aspects of early offspring behavior, including the development of locomotor activity and nipple attachment. This is experimental animal evidence and cannot establish the magnitude or nature of risk in humans.

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Human Brain Structure and Function

- Prenatal Cannabis and Tobacco Exposure in Relation to Brain Morphology: A Prospective Neuroimaging Study in Young Children

Biological Psychiatry | 2016
El Marroun et al.

Findings: Researchers compared brain imaging from children ages 6 to 8 with prenatal cannabis exposure, prenatal tobacco exposure, or neither exposure. Prenatal cannabis exposure was not associated with differences in total gray matter, white matter, or overall brain volume, but cannabis-exposed children had differences in cortical thickness, including thicker frontal cortices. The authors cautioned that additional research was needed to determine whether the association was causal.

- Prenatal Marijuana Exposure Impacts Executive Functioning Into Young Adulthood: An fMRI Study

Neurotoxicology and Teratology | 2016
Smith et al.

Findings: Young adults from the Ottawa Prenatal Prospective Study completed four executive-function tasks during functional MRI. Prenatal marijuana exposure was associated with differences in neural activity during executive-function processing that persisted into young adulthood. The study involved a small, intensively followed cohort, making the neuroimaging findings interesting but requiring caution when generalizing them to the broader population.

- Effects of Prenatal Marijuana on Visuospatial Working Memory: An fMRI Study in Young Adults

Neurotoxicology and Teratology | 2006
Smith et al.

Findings: Young adults with and without prenatal marijuana exposure performed similarly on a visuospatial working-memory task, but their brains did not function identically while performing it. Greater prenatal marijuana exposure was associated with increased activity in some brain regions and decreased activity in others. The authors interpreted this as evidence of altered neural processing persisting into young adulthood despite the absence of an observable difference in task performance.

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Clinical Guidance

- Committee Opinion No. 637: Marijuana Use During Pregnancy and Lactation

Obstetrics & Gynecology | 2015
American College of Obstetricians and Gynecologists Committee on Obstetric Practice

Guidance: This is a professional clinical recommendation, not an original research study. ACOG recommended that women who are pregnant or contemplating pregnancy discontinue marijuana use because of concerns about impaired neurodevelopment and the adverse effects associated with smoking. The committee also discouraged clinicians from prescribing or suggesting marijuana for medicinal purposes during preconception, pregnancy, and lactation.