The effects of military occupation on semen analysis

Abstract: Introduction: Infertility is becoming increasingly common, with a large contribution from male factor infertility. The majority of active-duty service members are men in their prime reproductive years. There are factors unique to the military that could impact fertility, including occupational, traumatic, and psychological exposures. However, there is limited research in the military population that analyzes a potential link between occupational exposures and the risk of male infertility.  Material and methods: A retrospective review of semen analyses was conducted between 2020 and 2022 at a large military treatment facility in the United States. The occupational code for each individual was queried from the Defense Manpower Data Center Reporting System (DMDCRS). Patients were excluded if their semen analysis was conducted after receiving a vasectomy or chemotherapy. If multiple semen analyses for a single individual were collected, the most favorable was selected. Results: A total of 1008 semen analyses were reviewed, of which 551 semen analyses met the inclusion criteria. There was no significant difference in sperm concentration, total motile count, or the number of individuals with low spermatozoa concentration (≤15 million/mL) between the occupational groups (p=0.77). A secondary analysis found that trainer pilots had significantly lower spermatozoa concentrations compared to fighter pilots (p= 0.028). Conclusions: This study did not find an increased risk of male infertility in any of the occupational groups. Strengths of this study include the large number of semen analyses included, focusing on the major portions of the semen analysis associated most with the risk for male infertility, and utilizing the DMDCRS to associate with potential work exposures, reducing risk for reporting bias. Weaknesses of the study include its retrospective nature, which could introduce selection bias given a mixture of individuals undergoing semen analysis for infertility or other reasons, the fact that semen analysis is a surrogate marker only for infertility, and that this was only conducted at a single military base. Different bases/missions may lead to variable exposures that could be associated with infertility. Future studies should increase the number of military bases included and consider longitudinal outcomes such as pregnancy or live birth rates. Assessing and minimizing the impact of military occupational exposures on the risk for male infertility is of particular importance due to the significant financial and emotional burden associated with the evaluation and treatment of infertility.