Large Danish Study Finds No Clear Link Between Cannabis Use and Male Fertility | Research

The takeaway

Among 1,058 young Danish men, ever using cannabis showed no association with semen quality, sperm count, or most reproductive hormones, though a slight FSH increase hinted at possible early testicular effects.

Men concerned about fertility, reproductive health researchers, clinicians counseling patients

No significant link to semen quality in 1,058 men

What the researchers found

In a cohort of 1,058 young men (59% had ever used cannabis), no associations were found between cannabis use and semen volume, concentration, total count, motility, morphology, or DNA fragmentation. The only signal was a non-significant 8% increase in FSH levels among ever-users (95% CI: -2% to 20%).

Why it matters

Previous studies on cannabis and male fertility have produced conflicting results, partly due to poor control for confounders. This study uniquely incorporates fetal-life exposure data, addressing a key limitation of prior research.

The numbers in context

1,058 men; 59% ever-used cannabis; no significant associations with any semen parameter; FSH 8% higher in ever-users (95% CI: -2% to 20%, not significant).

How the study worked

Sub-cohort of the Danish National Birth Cohort (Fetal Programming of Semen Quality cohort). 1,058 young men with self-reported cannabis use linked to clinical semen analysis, reproductive hormone measurements, and detailed information on fetal-life exposures.

What this study cannot tell us

Ever-use is a crude exposure measure that does not capture frequency, quantity, or recency. Self-reported cannabis use may underestimate actual exposure. Single semen sample per participant. Young age means long-term effects may not yet be apparent.

How to read the evidence

Large cohort with clinical outcomes and unique fetal exposure data, but crude cannabis exposure measure limits precision.

When this study was published

2025 publication

The bigger picture

The fertility question matters because cannabis is commonly used during reproductive years. This large, well-designed study largely provides reassurance, though the FSH elevation warrants monitoring as it could indicate subtle testicular stress.

Questions still open

Does heavy or current cannabis use (vs. ever-use) have different effects on semen quality?
Would the FSH elevation become significant with a more detailed cannabis exposure assessment?

Common questions

Does cannabis affect male fertility?

This large Danish study of 1,058 young men found no significant association between ever using cannabis and semen quality, sperm count, motility, or morphology. A slight increase in FSH was noted but was not statistically significant.

Should men trying to conceive avoid cannabis?

This study found no clear evidence that cannabis history affects semen quality. However, the study measured ever-use rather than current or heavy use, so heavy users may still want to exercise caution during conception attempts.

Read the original research

Ever cannabis use and biomarkers of male fecundity - A study in the Danish National Birth Cohort.

Reproductive toxicology (Elmsford, N.Y.), 137, 109004

View on PubMed ↗Publisher’s paper ↗

Citation

Khoury, Georges; Dan Hull, Sidsel; Ramlau-Hansen, Cecilia Høst; Sørensen, Anne Gaml; Hougaard, Karin Sørig; Petersen, Kajsa Ugelvig; Toft, Gunnar; Deen, Laura; Bonde, Jens Peter; Tøttenborg, Sandra Søgaard. (2025). Ever cannabis use and biomarkers of male fecundity - A study in the Danish National Birth Cohort.. Reproductive toxicology (Elmsford, N.Y.), 137, 109004. https://doi.org/10.1016/j.reprotox.2025.109004