Annual variation in semen characteristics and plasma hormone levels in men undergoing vasectomy

Reinberg, A; Smolensky, Michael H.; Hallek, Michael; Smith, Keith D.; Steinberger, Emil

doi:10.1016/s0015-0282(16)59721-0

Cited by 68 publications

(35 citation statements)

References 18 publications

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“…In fact, several external factors could affect genital temperature, together with environment. However, it is possible that the relationship between ambient temperature and semen parameters described here, reflects the known seasonal variation of semen parameters (Gyllenborg et al, 1999;Reinberg et al, 1988). Studies in animal models suggest that seasonal variations may be mediated by endogenous mechanisms related to the length of daylight (Levine, 1999;Thimonier, 1981).…”

Section: Discussionmentioning

confidence: 90%

Sperm quality and environment: A retrospective, cohort study in a Northern province of Italy

Santi

Vezzani

Granata

et al. 2016

Environmental Research

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Section: Discussionmentioning

confidence: 90%

Sperm quality and environment: A retrospective, cohort study in a Northern province of Italy

Santi

Vezzani

Granata

et al. 2016

Environmental Research

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“…More men from Denmark delivered their semen sample from September to February when the sperm concentration has been reported to be slightly higher than during the summer season (23)(24)(25)(26). This would result in a higher true difference than that reported.…”

Section: Discussionmentioning

confidence: 99%

Semen quality among Danish and Finnish men attempting to conceive. The Danish First Pregnancy Planner Study Team

Jensen¹,

Vierula²,

Hjøllund³

et al. 2000

Eur J Endocrinol

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Objective: To assess differences in semen quality between similar populations from Denmark and Finland. Design: Comparison of semen quality between 221 Finnish men (of whom 115 had no proven fertility) and 411 Danish men with no proven fertility in two follow-up studies among normal couples trying to conceive. Methods: In Finland male partners of couples without experienced infertility attempting to conceive were recruited through advertisements in local newspapers from 1984 to 1986. From 1992 to 1995 Danish men who lived with a partner and who had not attempted to achieve a pregnancy previously were recruited through their union when they discontinued birth control. All semen analyses were performed in accordance with the World Health Organization guidelines. Results: Median sperm concentration, total sperm count and the percentage of morphologically normal spermatozoa were significantly higher among the Finnish men without proven fertility (104.0 million/ml, 304.0 million and 58% respectively) compared with the Danish men (53.0 million/ml, 140.8 million, and 41% respectively). Sperm concentration was 105.7% (95% confidence interval (CI) 58.1%-167.6%) and total sperm count was 127.4% (95% CI 71.4%-201.6%) higher among Finnish men without proven fertility than among Danish men after control for confounders. Conclusions: Some, but hardly all, of the observed difference in semen quality may be explained by differences in recruitment procedures, selection of the men and by methodological differences in semen analysis between the two countries. Also a birth cohort effect may explain some of the differences between countries as the Finnish men were recruited 11 years before the Danish men. Therefore, follow-up studies with identical recruitment and selection of men from the two countries are needed.

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“…7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 Potential biological mechanisms supporting an association between vasectomy and incident prostate cancer include increases in androgen levels, which are hypothesised to increase the risk of prostate cancer,31 and impaired secretory function of the prostate, which might prolong exposure of the prostate to carcinogenic factors 11. Although some studies have shown an increase in serum dihydrotestosterone and testosterone after vasectomy,32 33 34 others have found no statistically significant change in androgen levels 3536 Similarly, findings on the association between frequency of ejaculation and risk of prostate cancer are conflicting 37…”

Section: Introductionmentioning

confidence: 99%

Vasectomy and risk of prostate cancer: population based matched cohort study

Nayan

Hamilton

Macdonald

et al. 2016

BMJ

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Objective To determine the association between vasectomy and prostate cancer, adjusting for measures of health seeking behaviour.Design Population based matched cohort study.Setting Multiple validated healthcare databases in Ontario, Canada, 1994-2012.Participants 326 607 men aged 20 to 65 who had undergone vasectomy were identified through physician billing codes and matched 1:1 on age (within two years), year of cohort entry, comorbidity score, and geographical region to men who did not undergo a vasectomy.Main outcomes measures The primary outcome was incident prostate cancer. Secondary outcomes were prostate cancer related grade, stage, and mortality.Results 3462 incident cases of prostate cancer were identified after a median follow-up of 10.9 years: 1843 (53.2%) in the vasectomy group and 1619 (46.8%) in the non-vasectomy group. In unadjusted analysis, vasectomy was associated with a slightly increased risk of incident prostate cancer (hazard ratio 1.13, 95% confidence interval 1.05 to 1.20). After adjustment for measures of health seeking behaviour, however, no association remained (adjusted hazard ratio 1.02, 95% confidence interval 0.95 to 1.09). Moreover, no association was found between vasectomy and high grade prostate cancer (adjusted odds ratio 1.05, 95% confidence interval 0.67 to 1.66), advanced stage prostate cancer (adjusted odds ratio 1.04, 0.81 to 1.34), or mortality (adjusted hazard ratio 1.06, 0.60 to 1.85).Conclusion The findings do not support an independent association between vasectomy and prostate cancer.

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Annual variation in semen characteristics and plasma hormone levels in men undergoing vasectomy

Cited by 68 publications

References 18 publications

Sperm quality and environment: A retrospective, cohort study in a Northern province of Italy

Sperm quality and environment: A retrospective, cohort study in a Northern province of Italy

Semen quality among Danish and Finnish men attempting to conceive. The Danish First Pregnancy Planner Study Team

Vasectomy and risk of prostate cancer: population based matched cohort study

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