Frequent Cannabis Use Before Pregnancy Strongly Predicts Use During Pregnancy
Among 40,806 pregnancies with preconception cannabis use, daily users were 2.7 times more likely to continue using during pregnancy, suggesting preconception screening could enable early intervention.
Quick Facts
What This Study Found
Daily preconception cannabis use was associated with 2.66 times greater risk of prenatal use compared to monthly or less use. Nearly half (45.1%) of all preconception cannabis users screened positive during pregnancy.
Key Numbers
40,806 pregnancies. 45.1% screened positive for prenatal use. Daily preconception use: aPR = 2.66 (95% CI: 2.59-2.73). Weekly: aPR = 1.99 (95% CI: 1.93-2.05). 65.7% non-White, 27.6% aged <25.
How They Did This
Retrospective observational study of 40,806 pregnancies (36,622 unique individuals) in Kaiser Permanente Northern California (2011-2022) with self-reported preconception cannabis use, using modified Poisson models.
Why This Research Matters
If frequency of preconception use predicts prenatal use this strongly, healthcare providers can identify high-risk individuals before pregnancy and provide targeted education and support.
The Bigger Picture
Cannabis use during pregnancy is a growing concern. Identifying that preconception use frequency is the strongest predictor enables a shift from pregnancy-stage intervention to preconception prevention.
What This Study Doesn't Tell Us
Single healthcare system in California. Self-report may underestimate use. Cannot account for all confounders. Excluded 2020 (pandemic year).
Questions This Raises
- ?Could preconception cannabis reduction programs prevent prenatal exposure?
- ?Should reproductive health screenings routinely include cannabis use frequency assessment?
Trust & Context
- Key Stat:
- Evidence Grade:
- Very large cohort with universal screening data and robust statistical methods — strong evidence for the dose-response relationship.
- Study Age:
- Recent study spanning over a decade of screening data (2011-2022) from a healthcare system with universal prenatal cannabis screening.
- Original Title:
- Association of preconception cannabis use frequency with cannabis use during early pregnancy.
- Published In:
- BMC pregnancy and childbirth, 25(1), 1044 (2025)
- Authors:
- Young-Wolff, Kelly C(42), Chi, Felicia W(6), Campbell, Cynthia I(16), Does, Monique B, Wysota, Christina N, Ansley, Deborah, Castellanos, Carley, Lapham, Gwen T
- Database ID:
- RTHC-08009
Evidence Hierarchy
Looks back at existing records to find patterns.
What do these levels mean? →Frequently Asked Questions
Does using cannabis before pregnancy mean you'll use it during?
Not necessarily, but the risk increases with frequency. Daily preconception users were 2.7 times more likely to continue during pregnancy than those using monthly or less.
What percentage of preconception users continue during pregnancy?
About 45% screened positive for prenatal cannabis use, including 24% by self-report and 37% by positive toxicology testing.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-08009APA
Young-Wolff, Kelly C; Chi, Felicia W; Campbell, Cynthia I; Does, Monique B; Wysota, Christina N; Ansley, Deborah; Castellanos, Carley; Lapham, Gwen T. (2025). Association of preconception cannabis use frequency with cannabis use during early pregnancy.. BMC pregnancy and childbirth, 25(1), 1044. https://doi.org/10.1186/s12884-025-08190-y
MLA
Young-Wolff, Kelly C, et al. "Association of preconception cannabis use frequency with cannabis use during early pregnancy.." BMC pregnancy and childbirth, 2025. https://doi.org/10.1186/s12884-025-08190-y
RethinkTHC
RethinkTHC Research Database. "Association of preconception cannabis use frequency with can..." RTHC-08009. Retrieved from https://rethinkthc.com/research/young-wolff-2025-association-of-preconception-cannabis
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.