Biomaterial Database

Geographic variations in sperm counts: a potential cause of bias in studies of semen quality. 1996

H Fisch, and E T Goluboff

Department of Urology, Squier Urologic Clinic, Columbia-Presbyterian Medical Center, New York, New York 10028, USA.

OBJECTIVE To determine whether geographic variations in sperm counts might bias conclusions drawn from studies of semen quality. METHODS Reanalysis of published data from a meta-analysis of 61 studies from 1938 to 1990 that concluded a worldwide decline in semen quality over the last 50 years. METHODS Influence of geographic location on sperm counts. RESULTS Of 61 studies in the meta-analysis, only 20 included > or = 100 men. These 20 studies collectively comprised 91% of the total men studied. We focused our reanalysis on these 20 studies. Of the studies before 1970, all were from the United States and 80% were from New York. These studies represented locations with the highest sperm counts. In contrast, after 1970, 80% of the studies were from locations not represented earlier, including five studies from third world countries, where sperm counts were low. CONCLUSIONS Sperm counts vary dramatically among different geographic locations.

UI	MeSH Term	Description	Entries
D007248	Infertility, Male	The inability of the male to effect FERTILIZATION of an OVUM after a specified period of unprotected intercourse. Male sterility is permanent infertility.	Sterility, Male,Sub-Fertility, Male,Subfertility, Male,Male Infertility,Male Sterility,Male Sub-Fertility,Male Subfertility,Sub Fertility, Male
D008297	Male		Males
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D012661	Semen	The thick, yellowish-white, viscid fluid secretion of male reproductive organs discharged upon ejaculation. In addition to reproductive organ secretions, it contains SPERMATOZOA and their nutrient plasma.	Seminal Plasma,Plasma, Seminal
D013076	Sperm Count	A count of SPERM in the ejaculum, expressed as number per milliliter.	Sperm Number,Count, Sperm,Counts, Sperm,Number, Sperm,Numbers, Sperm,Sperm Counts,Sperm Numbers
D015982	Bias	Any deviation of results or inferences from the truth, or processes leading to such deviation. Bias can result from several sources: one-sided or systematic variations in measurement from the true value (systematic error); flaws in study design; deviation of inferences, interpretations, or analyses based on flawed data or data collection; etc. There is no sense of prejudice or subjectivity implied in the assessment of bias under these conditions.	Aggregation Bias,Bias, Aggregation,Bias, Ecological,Bias, Statistical,Bias, Systematic,Ecological Bias,Outcome Measurement Errors,Statistical Bias,Systematic Bias,Bias, Epidemiologic,Biases,Biases, Ecological,Biases, Statistical,Ecological Biases,Ecological Fallacies,Ecological Fallacy,Epidemiologic Biases,Experimental Bias,Fallacies, Ecological,Fallacy, Ecological,Scientific Bias,Statistical Biases,Truncation Bias,Truncation Biases,Bias, Experimental,Bias, Scientific,Bias, Truncation,Biase, Epidemiologic,Biases, Epidemiologic,Biases, Truncation,Epidemiologic Biase,Error, Outcome Measurement,Errors, Outcome Measurement,Outcome Measurement Error