Summary:
A massive population-level epidemiological study of more than 2 million California hospital deliveries reveals that women diagnosed with cannabis use disorder during pregnancy face a threefold higher risk of requiring emergency psychiatric care during their first year postpartum. Conducted by researchers at UC Merced, Michigan State University, and UCLA, and published in the Annals of Epidemiology, the investigation revealed that 10% of pregnant women with cannabis use disorder had an acute postpartum psychiatric emergency visit, compared to under 3% of unexposed mothers. Tracking deliveries from 2016 through 2021, coinciding with recreational cannabis legalization, the authors recorded a 40% surge in gestational cannabis use disorder diagnoses, highlighting an urgent public health need for routine clinical screening and evidence-based maternal mental health support.
Key Facts:
- Triple the Rate of Acute Psychiatric Crises: Exactly 10% of women diagnosed with cannabis use disorder (CUD) during pregnancy presented to an emergency department for an acute psychiatric event in the postpartum year, compared to 15.6% for alcohol use disorder (AUD) and less than 3% for non-disorder controls.
- 40% Surge Post-Legalization: Between 2016 and 2021, the six-year window immediately following California’s recreational legalization, diagnoses of gestational cannabis use disorder climbed by 40%, whereas alcohol use disorder diagnoses remained static.
- Severe Clinical Threshold: The study focused strictly on acute hospital emergency visits for severe psychiatric disturbances, self-harm risks, and psychiatric crises, rather than mild or outpatient postpartum depressive symptoms.
Source: UC Merced / Annals of Epidemiology
As legal access to recreational and medicinal cannabis expands across North America, public perception of the drug has increasingly shifted toward regarding it as a benign, natural remedy. Driven in part by social media trends and commercial dispensaries marketing products for hyperemesis gravidarum (severe morning sickness), anxiety, and insomnia, an increasing number of expectant mothers perceive cannabis as a low-risk botanical alternative to conventional prescription psychotropics.
However, clinical reality often conflicts with popular perception. In a longitudinal epidemiological study analyzing state-mandated hospital discharge registries covering more than 2 million deliveries, researchers from the University of California, Merced, Michigan State University, and the University of California, Los Angeles, uncovered a strong association between problematic gestational cannabis consumption and severe psychiatric decompensation following childbirth.
Published in the Annals of Epidemiology, the research demonstrates that women diagnosed with cannabis use disorder (CUD) during pregnancy are more than three times as likely to require emergency department intervention for severe psychiatric disorders within the postpartum year compared to those without the disorder.
1 in 10 Face Acute Postpartum Crises
Led by Dr. Sidra Goldman-Mellor, associate professor of public health at UC Merced, and graduate researcher LaMecia De Alba, the team evaluated state hospital records from 2016 through 2021. The dataset stems from a National Institutes of Health (NIH) grant exploring the intersection of maternal substance use, violent victimization, and suicidal behavior across the perinatal spectrum.
The researchers analyzed three distinct maternal cohorts:
- Cannabis Use Disorder Cohort: Women receiving a clinical diagnosis of CUD—defined as continuous, compulsive cannabis consumption despite manifest damage to physical health, social relationships, or occupational responsibilities.
- Alcohol Use Disorder Cohort (AUD): Women diagnosed with clinical alcohol dependence during gestation.
- Control Cohort: Women delivering in the same hospital network without documented diagnoses of cannabis or alcohol use disorders.
The findings demonstrated a stark clinical trajectory: 10% of women diagnosed with CUD during pregnancy required emergency department intervention for a psychiatric crisis during the 12 months following delivery.
By comparison, 15.6% of mothers diagnosed with alcohol use disorder experienced a postpartum psychiatric emergency, whereas fewer than 3% of the control population required emergency mental healthcare.
“One in 10 of the women who were diagnosed with cannabis use disorder during pregnancy went on to have a psychiatric emergency department visit in the postpartum year,” said Goldman-Mellor. “These aren’t just women saying, ‘I feel depressed.’ These are psychiatric symptoms serious enough that they had to go to the emergency room.”
Legalization and the 40% Surge in Diagnoses
The study’s chronological boundary, spanning 2016 to 2021, captured the critical public health shift that unfolded after California voters passed Proposition 64, which legalized recreational adult-use cannabis.
Over this six-year period, diagnoses of gestational cannabis use disorder rose by 40% across California delivery wards. In contrast, hospital diagnoses of alcohol use disorder among pregnant women remained flat across the same timeframe.
“It suggests there is a growing population of women who are using cannabis to a problematic extent when they’re pregnant, and that group is at higher risk of serious psychiatric problems,” Goldman-Mellor noted.
The authors caution that widespread commercial availability has outpaced public awareness regarding potential neurological and psychiatric vulnerabilities.
“Just because it’s legal doesn’t necessarily mean that it’s safe,” Goldman-Mellor explained. “It’s like alcohol: Many people use it safely, but there’s a subset who become addicted, and that has really negative repercussions for their lives. As cannabis becomes more socially accepted, we have to pair that with education about real risks and with systems that actually screen and support pregnant and postpartum women who need help.”
Debunking the “Herbal Remedy” Misconception
Expectant mothers navigating pregnancy-related mood disturbances or physical nausea often turn to cannabis believing that natural compounds carry zero pharmacology-associated side effects.
“Some individuals don’t want to take prescribed medications because they know the side effects. With cannabis, there’s not much stated about the actual side effects,” said co-author LaMecia De Alba, whose research investigates drug misuse patterns among structurally vulnerable groups. “Some people think that because it’s an herbal remedy, there are no larger side effects.”
The authors emphasize that because modern commercial strains, concentrated wax extracts, and vaporization cartridges contain tetrahydrocannabinol (THC) concentrations exceeding 70% to 90%, historical assumptions regarding cannabis potency are scientifically obsolete.
“There’s still a lot to be learned about the potency or the frequency of cannabis products that are being used within specific populations, especially among pregnant and postpartum women,” added De Alba.
Correlation, High-Risk Markers, and Clinical Intervention
The investigators explicitly note that the study design captures observational epidemiological correlations rather than direct biological causality. The dataset cannot definitively resolve whether heavy cannabis consumption directly disrupts postpartum neuroendocrine pathways, or whether cannabis misuse serves as a behavioral marker for underlying trauma, severe chronic stress, or unmanaged psychiatric comorbidities.
“This study is not designed to prove that cannabis use disorder causes psychiatric emergencies,” Goldman-Mellor emphasized. “We didn’t set out to prove causation. What we wanted to show is that pregnant women who are addicted to cannabis are not a neutral group — this is a high-risk group.”
Rather than instituting punitive legal sanctions that discourage pregnant women from seeking prenatal care, the researchers urge the healthcare system to implement universal, compassionate, and non-stigmatizing screening during routine obstetric visits.
Integrating early substance screening with tailored maternal mental health services could allow clinicians to identify high-risk individuals before discharge, preventing acute psychiatric emergencies during the vulnerable postpartum transition.
Questions and Answers
What is the connection between cannabis use disorder during pregnancy and postpartum mental health?
In a study of over 2 million California births, 10% of women diagnosed with cannabis use disorder during pregnancy suffered a psychiatric emergency requiring a hospital visit in their postpartum year. This represents more than triple the rate seen in women without the diagnosis (less than 3%).
Did cannabis use disorder become more common after recreational legalization?
Yes. Between 2016 and 2021, hospital diagnoses of cannabis use disorder among pregnant women in California increased by 40%, whereas rates of alcohol use disorder remained steady.
Does this study prove that cannabis causes postpartum psychiatric crises?
No. The study identified a strong epidemiological correlation, not biological causation. Women with cannabis use disorder represent a high-risk group that may also face higher rates of preexisting mental health conditions, social stress, or trauma, indicating a critical need for early medical screening and psychological support.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this CUD and psychosis Research:
- Media Contact: Brenda Ortiz
- Source: University of California – Merced
- Image Credit: Image credited to Neuroscience News
- Original Research is Open Access: Annals of Epidemiology (Oct 1, 2026). “Prenatal cannabis use disorder and postpartum psychiatric emergency department visits: A retrospective cohort study of trends and associations in California, 2016–2021.” Authors: LaMecia De Alba, Claire E. Margerison, Alison Gemmill, and Sidra Goldman-Mellor.
- DOI: 10.1016/j.annepidem.2026.110271
Abstract
Prenatal cannabis use disorder and postpartum psychiatric emergency department visits: A retrospective cohort study of trends and associations in California, 2016–2021
Purpose
Cannabis is the most-used substance during pregnancy and has known associations with psychiatric disorders (e.g., psychosis, depression). No prospective studies, however, have investigated associations between prenatal cannabis use disorder (CUD) and psychiatric outcomes in perinatal populations.
Methods
Annual cohorts of women with a live infant delivery in California from 2016 to 2021 were constructed using statewide linked hospital and emergency department (ED) discharge data. We examined temporal trends in prenatal CUD prevalence and compared risk of postpartum psychiatric ED visits between delivering women with prenatal CUD, prenatal alcohol use disorder (AUD; included as a benchmark exposure), and neither disorder.
Results
The study sample included 2,036,016 delivering women. Between 2016 and 2021, prenatal CUD prevalence increased 1.0–1.4%. Postpartum psychiatric ED visits occurred in 10.4% of women diagnosed with CUD, 15.6% with AUD, and 2.7% with neither diagnosis. Relative to women with neither, those with CUD had ∼40% higher risk of any postpartum psychiatric ED visit (RRadj = 1.39, 95% CI: 1.32–1.47), while AUD was associated with 80% increased risk (RRadj = 1.80, 95% CI: 1.56–2.09).
Conclusion
Elevated risk of adverse psychiatric outcomes associated with CUD underscore the need for consistent screening, diagnosis, and treatment among perinatal women with CUD diagnoses.
