The studies focus on the effects of THC, the primary psychoactive compound in cannabis, and its potential role in triggering epigenetic alterations—chemical modifications that affect how genes are expressed without changing the underlying DNA sequence. Researchers say these changes may disrupt key genetic instructions required during the earliest stages of pregnancy.
Findings from Duke University indicate that regular exposure to cannabis was linked to altered DNA methylation patterns in sperm, particularly in genes active during early embryonic development. Higher THC levels in the body were associated with more pronounced changes, suggesting a dose-related relationship. Scientists involved in the research noted that these alterations could affect genes responsible for growth and developmental processes shortly after fertilisation.
One of the critical points highlighted in the research is the maternal-to-zygotic transition, a stage in early embryonic development when control shifts from maternal genetic material to the embryo’s own genome. Researchers suggest that if sperm carries disrupted epigenetic instructions, this transition may be affected, potentially interfering with normal embryo progression.
A related study from Boston University followed 1,535 couples attempting conception and reported that men who used cannabis at least once a week were associated with approximately double the risk of miscarriage compared with non-users. This pattern was observed even in cases where the female partner did not use cannabis, with the strongest association seen during the first eight weeks of pregnancy—a period known for heightened sensitivity in embryonic development.
The Duke study also identified epigenetic changes in a gene known as DLGAP2 gene, which is involved in brain cell communication and has previously been associated with neurodevelopmental conditions. Experimental work in animal models suggested that some of these changes may be heritable, raising questions about possible longer-term effects on offspring.
Researchers caution that increasing THC potency in modern cannabis products may further amplify potential risks, as average concentrations have risen significantly over recent decades. However, they also stress that the findings show associations rather than definitive causation across all cases, and further research is needed to fully understand the mechanisms involved.
Based on current evidence, the scientists involved recommend that men planning to conceive consider avoiding cannabis use for several months to allow for the natural regeneration of sperm without potential epigenetic disruption.
The studies add to a growing body of evidence suggesting that paternal health and lifestyle choices may play a more significant role in reproductive outcomes than previously understood.