Cannabis Use Before and During Pregnancy Is Linked to Worse Morning Sickness
In 356,343 pregnancies, daily prenatal cannabis use was associated with 3.8 times greater odds of severe nausea and vomiting, challenging the common belief that cannabis helps with morning sickness.
Quick Facts
What This Study Found
Daily prenatal cannabis use was associated with 3.80x odds of severe NVP and 1.97x odds of mild NVP. Even preconception daily use predicted 2.61x odds of severe NVP, suggesting either reverse causation or that chronic use sensitizes the vomiting response.
Key Numbers
356,343 pregnancies. 11.3% preconception use, 6.5% prenatal use. 3.6% diagnosed with severe NVP, 16% mild NVP. Daily prenatal use: severe NVP aOR = 3.80 (95% CI: 3.28-4.39), mild NVP aOR = 1.97 (95% CI: 1.79-2.17).
How They Did This
Cross-sectional analysis of 356,343 pregnancies in Kaiser Permanente Northern California (2011-2022) with universal screening for cannabis use and ICD-coded NVP diagnoses.
Why This Research Matters
Many pregnant individuals use cannabis specifically to treat morning sickness. This large study suggests the opposite — that cannabis use is associated with worse nausea and vomiting, possibly through a mechanism similar to cannabinoid hyperemesis syndrome.
The Bigger Picture
The paradox of using cannabis for nausea while it may worsen nausea during pregnancy mirrors the CHS phenomenon. This challenges a widespread belief and has immediate clinical implications for prenatal counseling.
What This Study Doesn't Tell Us
Cross-sectional design cannot determine direction of causation — women with worse NVP may use more cannabis to cope. ICD codes may undercount NVP. Cannabis use frequency is self-reported.
Questions This Raises
- ?Is cannabis causing worse NVP, or are women with worse NVP using more cannabis?
- ?Could the mechanism be related to cannabinoid hyperemesis syndrome?
Trust & Context
- Key Stat:
- Evidence Grade:
- Very large population study with universal screening, but cross-sectional design cannot establish causation — reverse causation is a significant concern.
- Study Age:
- Recent analysis spanning 2011-2022, providing the largest study to date on cannabis use and pregnancy nausea.
- Original Title:
- Frequency of Preconception and Prenatal Cannabis Use and Nausea and Vomiting in Pregnancy.
- Published In:
- Obstetrics and gynecology, 145(5), 519-522 (2025)
- Authors:
- Young-Wolff, Kelly C(42), Chi, Felicia W(6), Campbell, Cynthia I(16), Alexeeff, Stacey E, Ansley, Deborah, Vanderziel, Alyssa, Lapham, Gwen T
- Database ID:
- RTHC-08011
Evidence Hierarchy
A snapshot of a population at one point in time.
What do these levels mean? →Frequently Asked Questions
Does cannabis help with morning sickness?
This large study actually found the opposite association — daily cannabis use during pregnancy was linked to 3.8x higher odds of severe nausea and vomiting. However, this could also mean women with worse symptoms use more cannabis.
Why would cannabis make nausea worse?
The mechanism is unclear but may parallel cannabinoid hyperemesis syndrome, where chronic heavy cannabis use paradoxically causes severe vomiting. The endocannabinoid system plays complex roles in nausea regulation.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-08011APA
Young-Wolff, Kelly C; Chi, Felicia W; Campbell, Cynthia I; Alexeeff, Stacey E; Ansley, Deborah; Vanderziel, Alyssa; Lapham, Gwen T. (2025). Frequency of Preconception and Prenatal Cannabis Use and Nausea and Vomiting in Pregnancy.. Obstetrics and gynecology, 145(5), 519-522. https://doi.org/10.1097/AOG.0000000000005884
MLA
Young-Wolff, Kelly C, et al. "Frequency of Preconception and Prenatal Cannabis Use and Nausea and Vomiting in Pregnancy.." Obstetrics and gynecology, 2025. https://doi.org/10.1097/AOG.0000000000005884
RethinkTHC
RethinkTHC Research Database. "Frequency of Preconception and Prenatal Cannabis Use and Nau..." RTHC-08011. Retrieved from https://rethinkthc.com/research/young-wolff-2025-frequency-of-preconception-and
Access the Original Study
Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.
This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.