Background The influence of marijuana use on human fertility has not been well studied. We evaluated the association between female and male use of marijuana and fecundability in Pregnancy Study Online, a prospective cohort of North American couples.
Methods Female participants completed a baseline questionnaire on which they reported lifestyle and behavioural factors, including frequency of marijuana use within the previous 2 months. Male partners completed an optional baseline questionnaire on similar factors, including marijuana use. Women completed follow-up questionnaires every 8 weeks for 12 months or until pregnancy, initiation of fertility treatment or loss to follow-up, whichever came first. The analysis was restricted to 4194 women (1125 couples) with ≤6 cycles of pregnancy attempt time at study enrolment (2013–2017). Fecundability ratios (FR) and 95% CIs were estimated using proportional probabilities regression models, with adjustment for potential confounders.
Results Men (14.2%) were more likely than women (11.6%) to be marijuana users. FRs for female marijuana use <1 and ≥1 time/week relative to non-use were 0.99 (95% CI 0.85 to 1.16) and 0.98 (95% CI 0.80 to 1.20), respectively. FRs for male marijuana use <1 and ≥1 time/week relative to non-use were 0.87 (95% CI 0.66 to 1.15) and 1.24 (95% CI 0.90 to 1.70), respectively. Associations for frequent marijuana use (≥1 time/week) were attenuated among non-smoking men (FR=1.21, 95% CI 0.84 to 1.74), but stronger among men reporting intercourse ≥4 times/week (FR=1.35, 95% CI 0.72 to 2.53).
Conclusions In this preconception cohort study, there was little overall association between female or male marijuana use and fecundability.
- environmental epidemiology
- cohort studies
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Contributors EEH, KJR, EMM, HTS and LAW designed the research. EEH, KJR, EMM, HTS, AKW, LAW and SM conducted the research. LAW analysed the data. AKW and LAW coded the outcome and covariate data. LAW took the lead in writing the manuscript. LAW has primary responsibility for the final content. All authors read and approved the final revised manuscript.
Funding Funding was provided by NICHD (R21-HD072326; R01-HD086742; R03 HD090315); the Boston University Reproductive, Perinatal and Pediatric Epidemiology Training Grant (T32-HD052458); and the Reproductive Scientist Development Program (5K12HD000849-27).
Competing interests None declared.
Ethics approval Study approval was obtained from Boston Medical Center Institutional Review Board.
Provenance and peer review Not commissioned; externally peer reviewed.
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