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Indian Journal of Medical Sciences, Vol. 58, No. 7, July, 2004, pp. 305-306 Letter To Editor Is today's male population really less fertile? Declining semen quality - A global phenomenon? DSouza Urban JA, DSouza Vilma M, Narayana K Department of Physiology, School of Medical Sciences-PPSP, Universiti Sains Malaysia - 16150, K. Kerian, Kelantan Code Number: ms04054 Sir, Scientific data published in recent time presents a conflicting record on semen quality and sperm count in men around the world. There seems to be a strong controversy on the decline in sperm count and semen quality over the data published since 50 years. Evaluation of semen quality over a period of 11 years in subjects attending a fertility clinic in India contradicts the earlier reports, suggesting the fact of declining sperm count as not a global phenomenon.[1] But meta-analysis of 61 studies between 1938 - 1991, in 14,947 semen samples of fertile men from 23 countries conclusively confirmed a decline in sperm count. In addition a birth cohort study provides a direct evidence of deteriorating semen quality in Scottish men in a chronological order.[2] Reanalysis of data on mean sperm count and their temporal distribution using different statistical tests; quadratic, spline fit and stairstep, suggesting a constant or slightly increase in sperm count over the years argue the fact of data analysis using linear regression model as inappropriate and concludes that, selection bias,[3] variability in semen collection method, lack of adherence to minimum abstinence period, conflicting data from a large laboratory and a variety of statistical analysis models used are the factors responsible for the biased decline in count over the years.[4] But reports on a decline in semen quality seem difficult to reconcile with the absence of any detectable decrease in fertility index. Modern society has been witnessing a rapid growth of chemical, industrial and pharmaceutical hazards. Exposure to environmental pollution, estrogen and estrogenic compounds, endocrine disruptors and potential compounds like pesticides were implicated as the possible factors affecting spermatogenesis. Geographic differences in semen quality with a reduced sperm concentration and motility in semi rural and agricultural areas relative to urban and less agricultural areas is further evidence for the potential environmental pollutants affecting the male fertility.[5] Recent report contradicting the previous reports in the literature on the trend of sperm count and semen quality[1] is quiet interesting and challenges the assertions of past literature. Apart from differences in selection criteria, abstinence period and methodology factors, climate, smoking, alcohol intake, ethnicity, seasonal variation, social and economic status also merit further consideration while investigation. Hence the recent report contradicting the earlier findings, reinforce to critically view the trend of declining semen quality and cannot be concluded on the global status of male fertility on the basis of the report from a single fertility clinic of a vast country with a high population density. On this issue regulatory and research agencies involving reproductive scientists, clinicians need to work on a common platform from different countries around the world and should undertake studies on common guidelines put forth by WHO to confirm or to refute the hypothesis. Current WHO guidelines for normal semen quality also should be used with caution as some men with sperm counts above the lower limit of WHO defined normal range found to be sub fertile.[6] This it cannot be concluded on a whole depending on data from one fertility health clinic in India. Similar epidemiological survey from different parts of India with identical recruitment and selection of men may add support on their findings. Further feasibility of a prospective study of fertility and an established study base is important to provide useful information on risk of fertility. Delay in confirmation of the conflicting reports may compromise the fertility index of future. REFERENCES
Copyright 2004 - Indian Journal of Medical Sciences |
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