Abstract
This meta-analysis, following our previous reports those documented an overall 57% diminution in mean sperm concentration around the globe over past 35 years and 32.5% decline in past 50 years in European population, attempts to report the declining trend of sperm concentrations in African population between 1965 and 2015. In the course of retrieval of data following MOOSE guidelines and PRISMA checklist, we found a total of fourteen studies that have been conducted during that period on altering sperm concentration in the African male. Following analysis of the data, a time-dependent decline of sperm concentration (r = -0.597, p = 0.02) and an overall 72.6% decrease in mean sperm concentration was noted in the past 50 years. The major matter of concern is the present mean concentration (20.38×106/ml) is very near to WHO cut-off value of 2010 of 15×106/ml. Several epidemic diseases, genital tract infection, pesticides and heavy metal toxicity, regular consumption of tobacco and alcohol are reported as predominant causative factors. This comprehensive, evidence-based meta-analysis and systematic review concisely presents the evidence of decreased sperm concentration in the African male over past 50 years with possible causative factors to serve the scientific research zone related to male reproductive health.
Highlights
A worldwide decline in sperm count has been presented vastly in past few decades through several studies[1,2]
During the retrieval of relevant documents, we found only fourteen studies which had been conducted on alterations of sperm concentration of African population in the last 50 years
The current meta-analysis, with pertinent evidence reports an overall 73% decline in sperm concentration in African men over past 50 years and the current concentration is very near to WHO cut-off value of 2010 which is a major issue of concern
Summary
A worldwide decline in sperm count has been presented vastly in past few decades through several studies[1,2]. In 1992, Carlsen et al reported a global decline in sperm counts in a meta-analysis of 61 studies between 1938 and 1990 evaluating the semen analyses of 14,947 presumably fertile men from 23 countries[4]. We have reported decline in semen volume[10] and sperm count[11] in males over past few decades.
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