Most Men With Varicocele Are Fertile, but the Number of Offspring Is Reduced

Varicocele is the most common identifiable cause of male infertility [1]. While only some men with varicocele develop infertility, most are considered fertile. Clinically, a man is categorized as fertile if he has fathered at least one child, even with a varicocele. However, since varicocele is implicated in over 80% of men with secondary infertility [2], many who conceive their first child naturally may be unable to conceive again, leaving couples with only one child despite a desire for more. If true, the high prevalence of varicocele could contribute to declining birth rates. We investigated men aged 40 years and older who had completed family planning and underwent health checkups at Ube Central Hospital between April 2007 and March 2024. Reproductive history, number of children, and lifestyle factors were recorded, and physical examinations assessed testicular volume with a punched-out orchid meter and the presence of varicocele. Men who had undergone fertility treatment, either themselves or through partners, were excluded. The study was approved by the Institutional Review Board. Statistical analyzes used unpaired t-tests, with p < 0.05 considered significant. A total of 756 men with a mean age of 57.3 years were included in the analysis. Varicocele was identified in 137 men (18.1%) (Figure 1A). Men with varicocele had significantly smaller testicular volumes bilaterally compared to those without, while no significant differences were observed in age, current body mass index (BMI), current or past smoking history, or current comorbidities. The rate of having at least one child (fertility rate) did not differ significantly between men with and without varicocele (Figure 1B). However, the proportion of men with two or more children was significantly lower in the varicocele group (13.9%) compared to the non-varicocele group (76.7%, p < 0.0001; Figure 1C), and the average number of children was also significantly lower among men with varicocele (1.16 vs. 2.01, p < 0.0001; Figure 1D). Studies examining the relationship between male factors and number of children are extremely limited [3, 4]. The Norwegian cohort reported associations between male smoking or high BMI and both reduced number of children and delayed age at first childbirth. One potential explanation for preserved fertility in some men with varicocele is the presence of intrinsic antioxidant systems in the testes, which may protect spermatogenesis despite elevated scrotal temperatures [5]. This is the first report to evaluate the number of children among fertile men with varicocele, and our results demonstrate that although they may achieve conception, the overall number of offspring is significantly reduced. Recent meta-analyzes have shown that varicocele repair improves semen parameters [6], suggesting that surgical treatment may not only prevent infertility but also reduce secondary infertility and increase the number of children in couples desiring additional offspring. Several limitations should be acknowledged. Data on sexual frequency during the reproductive period were not available. Current smoking status, BMI, and comorbidities may differ from those during the period of family planning. On the other hand, the current patient characteristics reflect the average profile of Japanese men, and therefore we consider that the findings from this cohort can be generalized. As confounding factors, such as sexual frequency, partner fertility, and lifestyle factors during reproductive years, were not available in our dataset, this warrants further investigation in studies where these variables can be more precisely measured. Nonetheless, this study captures a fundamental endpoint in reproductive medicine—the number of offspring—and provides valuable insights for counseling infertile couples, preconception care for men, and possibly for addressing the declining birth rate. Varicocele may not prevent initial conception, especially when partner fertility is high, but its chronic adverse effects on spermatogenesis and testicular function can reduce later reproductive potential and lower offspring number. Thus, varicocele may influence cumulative fertility more than the chance of first conception. This distinction is important for understanding broader reproductive implications. In Japan, strategies to address declining birth rates focus mainly on social and economic support, with little attention to medical factors. Our findings suggest proactive varicocele treatment could enhance national fertility outcomes and contribute to countermeasures against population decline. While the present results raise the possibility that addressing varicocele may have broader reproductive implications, confirmation from prospective interventional studies is required before drawing conclusions about its impact on national fertility rates. R6-108. Koji Shiraishi: conceptualization, methodology, investigation, formal analysis, data curation, writing – original draft, writing – review and editing. The author has nothing to report. Koji Shiraishi is an Editorial Board member of the International Journal of Urology and a co-author of this article. To minimize bias, he was excluded from all editorial decision-making related to the acceptance of this article for publication.