In a study of more than 2 million California deliveries, 10 percent of women diagnosed with the disorder had a psychiatric emergency visit in their first postpartum year, compared with 2.7 percent of women without the disorder.
What the California Study Found
UC Merced public health professor Sidra Goldman-Mellor and graduate student LaMecia De Alba led the research. They also had collaborators from Michigan State University and UCLA. Their findings were published in the Annals of Epidemiology.
Using hospital delivery records from 2016 through 2021, compared psychiatric emergency department visits during the postpartum year among three groups.
Those groups were women diagnosed with cannabis use disorder, women diagnosed with alcohol use disorder and a control group without either diagnosis.
UC Merced reports that it was less than 3 percent among women without either disorder, with 2.7 percent given as the comparison for those without cannabis use disorder.
Overall, cannabis use disorder during pregnancy was found to be linked to a 40 percent higher risk of a psychiatric emergency visit during the first postpartum year.
Goldman-Mellor emphasized that these were symptoms that were serious enough to require an emergency department visit.
The study doesn’t show that every participant with a diagnosis experienced a crisis, nor does it identify which individual patients will actually need emergency care.
Diagnoses Increased During the Study Period
Across the six-year study period, diagnoses of cannabis use disorder among pregnant women in California rose by about 40 percent. The incidence of alcohol use disorder remained notably flat.
The researchers describe a growing population using cannabis to a problematic extent during pregnancy. Cannabis use disorder is a medical diagnosis for people who continue using cannabis despite harm to their health, relationships, or responsibilities.
The increase in diagnoses should not be paraphrased as definitive proof that cannabis use itself increased by the same amount.
The study period began as California voters approved recreational cannabis use in the state. Goldman-Mellor said legalization does not establish safety and compared the situation with alcohol. Many people use it, while a subset develops addiction with negative consequences.
De Alba added that some people choose cannabis because they want to avoid side effects from prescribed medications or assume an herbal remedy has no broader side effects.
The researchers also said more work is needed on the potency and frequency of cannabis products used within specific populations, especially during pregnancy and the postpartum period.
Addiction Treatment and Pregnancy Screening
The study was part of a broader National Institutes of Health grant examining substance use, violence victimization and self-harm behavior among pregnant and postpartum women.
Its treatment relevance lies in identifying a group that may need earlier screening and support for both substance use and psychiatric symptoms.
The findings support asking about cannabis use disorder rather than assuming legal or widely accepted use is clinically irrelevant. They also support making mental health treatment part of the conversation when cannabis use disorder is identified during pregnancy.
The source doesn’t compare treatment programs or show that a specific intervention reduces emergency visits. It identifies an association and a screening need.
Readers shouldn’t interpret it as evidence that entering rehab will produce a particular postpartum outcome.
Why the Association Does Not Prove Cause
Goldman-Mellor explicitly cautioned that the study wasn’t designed to prove cannabis use disorder causes psychiatric emergencies.
The records show an association between the diagnosis and later emergency visits, which leaves open the influence of other factors.
A cannabis use disorder diagnosis can help identify elevated risk without explaining every part of a person’s mental health or predicting an inevitable crisis. The researchers describe the group as high-risk.
They don’t describe it as a neutral comparison group and not as people destined to experience an emergency.
The available UC Merced report also does not provide adjusted risk estimates for every possible confounding factor.
Its clearest practical message is that screening and support should address substance use and psychiatric needs together.
What This Means for Treatment Seekers
Anyone comparing treatment options during pregnancy or after delivery can ask whether a provider screens for cannabis use disorder, coordinates with prenatal and postpartum clinicians and assesses psychiatric symptoms.
Families can also ask how a program responds when a person experiences an emerging mental health crisis.
The study offers providers evidence for paying closer attention during intake and follow-up. It offers patients a reason to discuss cannabis use honestly with a qualified clinician without assuming that legal status answers the health question.
Exploring Treatment Options
When you compare rehab centers, be sure to verify whether the facility treats the specific substance use disorder involved and whether it provides or coordinates mental health treatment.
Pregnant and postpartum patients should also ask how care is coordinated with their obstetric and pediatric providers.
Rehab.com’s directory includes addiction treatment and mental health treatment options across the country.
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