Both maternal and paternal cannabis use during pregnancy were linked to psychotic-like experiences in children at age 10
In a birth cohort of 3,692 children, both maternal cannabis use (38% higher risk) and paternal cannabis use (44% higher risk) during pregnancy were associated with more psychotic-like experiences at age 10, suggesting genetic rather than direct prenatal exposure effects.
Quick Facts
What This Study Found
Researchers followed 3,692 children from the Generation R birth cohort to examine whether parental cannabis use during pregnancy affected the risk of psychotic-like experiences at age 10. They used a clever study design: comparing maternal versus paternal cannabis use to disentangle direct prenatal exposure effects from shared genetic/familial factors.
Maternal cannabis use during pregnancy was associated with a 38% increase in offspring psychotic-like experiences. But critically, paternal cannabis use during pregnancy showed a nearly identical association (44% increase), even though fathers do not directly expose the fetus.
Furthermore, maternal cannabis use exclusively before pregnancy (but not during) showed similar associations to continued use during pregnancy, suggesting the timing of exposure mattered less than the fact that the parent used cannabis.
This pattern strongly suggests that shared genetic vulnerabilities or familial factors, rather than direct chemical exposure of the fetus to cannabis, largely explain the association between parental cannabis use and offspring psychotic-like experiences.
Key Numbers
3,692 participants from Generation R cohort. Maternal cannabis use: adjusted OR = 1.38 (95% CI 1.03-1.85). Paternal cannabis use: adjusted OR = 1.44 (95% CI 1.14-1.82). Pre-pregnancy-only maternal use showed comparable estimates to continued use during pregnancy. Offspring assessed at age 10.
How They Did This
This prospective cohort study was embedded in the Generation R birth cohort (N = 3,692). Maternal cannabis exposure was verified using both self-reports and urine cannabis metabolite levels. Paternal cannabis use was reported by mothers. Offspring psychotic-like experiences were assessed at age 10. Adjusted odds ratios were calculated controlling for confounders.
Why This Research Matters
This study provides a more nuanced understanding of why children of cannabis-using parents may develop psychotic-like experiences. Rather than cannabis directly damaging the developing fetus, the finding that paternal use shows the same association points to shared genetics and family environment as the primary pathway. This has implications for how we counsel families and design prevention strategies.
The Bigger Picture
This study reframes the cannabis-psychosis link from a purely environmental exposure narrative to one involving shared genetic vulnerability. The fact that a father's cannabis use during the pregnancy period predicts offspring psychosis risk as strongly as the mother's direct fetal exposure is a powerful argument for genetic confounding in the cannabis-psychosis literature.
What This Study Doesn't Tell Us
Psychotic-like experiences at age 10 are subclinical and may not develop into psychotic disorders. Paternal cannabis use was reported by mothers, which may be less accurate than direct reporting. The study cannot completely rule out indirect paternal effects (secondhand smoke exposure, parenting behavior). Self-reported cannabis use may underestimate actual use.
Questions This Raises
- ?What specific genetic variants are shared between cannabis use propensity and psychosis vulnerability?
- ?Does the finding that paternal use shows similar risk change how prenatal cannabis counseling should be framed?
- ?Will children with psychotic-like experiences at 10 develop clinical psychosis later?
Trust & Context
- Key Stat:
- Paternal cannabis use (44% increase) predicted child psychosis risk as much as maternal use (38%)
- Evidence Grade:
- This is a large prospective birth cohort with verified maternal exposure and clever paternal comparison design, providing moderate evidence for shared genetic mechanisms.
- Study Age:
- Published in 2018. The Generation R cohort continues to produce follow-up data on these children.
- Original Title:
- Maternal and paternal cannabis use during pregnancy and the risk of psychotic-like experiences in the offspring.
- Published In:
- Schizophrenia research, 202, 322-327 (2018)
- Authors:
- Bolhuis, Koen, Kushner, Steven A, Yalniz, Selda, Hillegers, Manon H J, Jaddoe, Vincent W V, Tiemeier, Henning, El Marroun, Hanan
- Database ID:
- RTHC-01598
Evidence Hierarchy
Enrolls participants and follows them forward in time.
What do these levels mean? →Frequently Asked Questions
Does cannabis use during pregnancy cause psychosis in children?
This study found that parental cannabis use was associated with more psychotic-like experiences in children, but the fact that paternal use (which doesn't directly expose the fetus) showed the same association suggests shared genetics rather than direct fetal harm are the main explanation.
Should fathers stop using cannabis during pregnancy?
While this study cannot prove that paternal cannabis use directly harmed children, it does show that families where either parent uses cannabis have higher rates of offspring psychotic-like experiences. This likely reflects shared genetic vulnerabilities that warrant awareness and monitoring.
Read More on RethinkTHC
Cite This Study
https://rethinkthc.com/research/RTHC-01598APA
Bolhuis, Koen; Kushner, Steven A; Yalniz, Selda; Hillegers, Manon H J; Jaddoe, Vincent W V; Tiemeier, Henning; El Marroun, Hanan. (2018). Maternal and paternal cannabis use during pregnancy and the risk of psychotic-like experiences in the offspring.. Schizophrenia research, 202, 322-327. https://doi.org/10.1016/j.schres.2018.06.067
MLA
Bolhuis, Koen, et al. "Maternal and paternal cannabis use during pregnancy and the risk of psychotic-like experiences in the offspring.." Schizophrenia research, 2018. https://doi.org/10.1016/j.schres.2018.06.067
RethinkTHC
RethinkTHC Research Database. "Maternal and paternal cannabis use during pregnancy and the ..." RTHC-01598. Retrieved from https://rethinkthc.com/research/bolhuis-2018-maternal-and-paternal-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.