***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: Recent prospect i ve studies of male reproductive health have shown differences between several European countries . Our objective was to evaluate the current situation in the two Baltic States Estonia and Lithuania . In 1997 - 99 we investigated  semen parameters , levels of reproductive hormones and general health factors  of 196 men from the general population in Lithuania ; from Estonia , 79 men from the general population and 118 soldiers were investigated . Adjusted for interlaboratory differences and abstinence period , sperm concentration of Lithuanian and Estonian men from the general population s were shown to be 55 and 67 million/mL , respectively . The Estonian soldiers had the highest sperm concentration , 82 million/mL. The frequencies of morphologically normal spermatozoa were 6.2 , 7.7 and 9.6 % , respectively . In contrast to the semen qualities , highest Inhibin B levels were detected in the Lithuanians ( 233 pg/mL ) followed by Estonian men from the general population ( 220 pg/mL ) and Estonian soldiers ( 185 pg/mL ) . The soldiers had also the lowest level of testosterone and oestradiol . The sperm counts of the Estonian and Lithuanian men investigated here are higher than recently shown for Norwegian , Danish , Estonian and Finnish men . Comparisons should be cautiously drawn as the groups are not completely comparable . Still , even within the Baltic region , geographically close and sharing common recent social history , differences in semen quality and levels of reproductive hormones are apparent Semen analyses was carried out in a population of 1250 r and omly selected Libyan males .  Two semen sample s collected from each volunteer were subjected to the routine analyses following the World Health Organization recommendations . The Libyan population had a higher percentage of men with sperm density in the range of 40 - 60 millions/ml . The percentage of men with sperm counts above 100 millions/ml is comparatively lower than that is reported by MacLeod and Gold ( 9 ) . The seminal plasma transferrin levels showed a positive correlation with sperm density and alpha-glucosidase activity with sperm motility Population studies have shown that a high proportion of Nordic men may have so poor semen quality that they can be classified as sub-fertile according to international st and ards . A question is whether the Nordic data are specific for the Nordic countries or they should be seen as an expression of a general trend in Europe . We therefore carried out a prospect i ve study of semen quality of young men raised in the former East Germany ( Leipzig ) and West Germany ( Hamburg ) . To enable inter-regional comparisons , we utilized a common European research protocol previously used in studies in the Nordic-Baltic region . Three hundred and thirty-four young men representative of the general population from Hamburg , and 457 from Leipzig delivered semen sample s  , underwent physical examinations and provided information on life-style and reproductive health parameters . The study period in Hamburg was February 2003 - -July 2004 , and in Leipzig July 2003 - -April 2005 . No significant differences were observed in sperm concentration ( median 46 , 42 , and 44 million/mL for men from Hamburg , Leipzig and the combined Hamburg-Leipzig group respectively ) or total sperm count ( 154,141 and 149 million ) , whereas the differences for morphologically normal spermatozoa ( 9.4 and 8.4 % ) and motile spermatozoa ( 67 and 81 % ) were significantly different . Previously published studies have shown reduced fertility with decreasing sperm concentrations below 40 - 55 millions/mL and normal sperm morphology below 9 - 19 % . Thus , a large fraction of young German men seem to have impaired semen quality that may reduce their natural fertility . However , it remains to be investigated to what extent poor semen quality contributes to the low German fertility rates OBJECTIVE To determine the consequences of adjuvant testicular germ cell tumor treatment ( TGCT )  on sperm characteristics and sperm DNA , and to evaluate the predictors of sperm recovery . DESIGN Multicenter prospect i ve longitudinal study of patients analyzed before treatment and after 3 , 6 , 12 , and 24 months . SETTING University hospitals . PATIENT(S ) One hundred twenty-nine volunteer TGCT patients and a control group of 257 fertile men . INTERVENTION(S ) Routine semen analyses , sperm DNA , and chromatin assessment s. MAIN OUTCOME MEASURE(S ) Comparisons of mean sperm characteristics before and after treatment , with sperm recovery analyzed by the Kaplan-Meier method . RESULT ( S ) The quantitative and qualitative sperm characteristics decreased after treatment , with lowest values at 3 and 6 months and with variations according to treatment type . The mean total sperm count recovered to pretreatment values at 12 months after treatment after two or fewer bleomycin , etoposide , and cisplatin ( BEP ) cycles , but not after radiotherapy or more than two BEP cycles . Only the treatment modalities and pretreatment sperm production were related to recovery of the World Health Organization reference sperm values . An increased proportion of patients had elevated high sperm DNA stainability at 6 months after radiotherapy . CONCLUSION ( S ) Adjuvant treatments for testicular germ cell tumor have drastic effects on spermatogenesis and sperm chromatin quality . These new data on both the recovery period according to treatment modalities and the post-treatment chromatin status of sperm are useful tools for counseling patients wishing to conceive AIM To analyze factors influencing the efficacy of hormonal suppression of spermatogenesis for male contraception . METHODS A nested case-control study was conducted , involving 43 subjects , who did not achieve azoospermia or severe oligozoospermia when given monthly injections of 500 mg testosterone undecanoate ( TU )  , defined as partial suppressors compared with 855 subjects who had suppressed spermatogenesis ( complete suppressors ) .  Sperm density , serum testosterone , luteinizing hormone ( LH ) and follicle stimulating hormone ( FSH ) concentrations at the baseline and the suppression phase were compared between partial and complete suppressors . Polymorphisms of and rogen receptor ( AR ) and three single nucleotide variants and their haplotypes of FSH receptor ( FSHR ) genes determined by polymerase chain reaction ( PCR ) and DNA sequencing technique were compared between 29 partial and 34 complete suppressors . RESULTS Baseline serum LH level was higher and serum LH as well as FSH level during the suppression phase was less suppressed in partial suppressors . Additionally , in a logistic regression analysis larger testis volume , higher serum FSH concentrations alone , or interaction of serum LH , FSH , testosterone and sperm concentrations were associated with degree of suppression . The distribution of polymorphisms of AR or FSH receptor genes did not differ between partial and complete suppressors . In cases with incomplete FSH suppression ( FSH 0.2 IU/L ) , the chances of reaching azoospermia were 1.5 times higher in the subjects with more than 22 CAG triplet repeats . CONCLUSION Partial suppression of spermatogenesis induced by 500 mg TU monthly injections is weakly influenced by hormonal and clinical features but not polymorphism in AR and FSHR genes STUDY QUESTION Are urinary phthalate concentrations associated with altered semen quality parameters among males recruited from the general population ? SUMMARY ANSWER Urinary levels of metabolites of phthalate diesters are associated with lower total sperm counts , larger sperm head sizes , and higher percentages of morphologically abnormal sperm . WHAT IS KNOWN ALREADY High dose experiments in rats implicate phthalates as anti- and rogens . Studies involving infertile men seeking care suggest that phthalates influence measures of semen quality raising concern about the implication s for men in the general population . STUDY DESIGN , SIZE , DURATION This prospect i ve cohort study comprised 501 male partners in couples discontinuing contraception to become pregnant , who were recruited from 16 US counties using population -based sampling frameworks from 2005 to 2009 . PARTICIPANTS / MATERIAL S , SETTING , METHODS Urine and semen sample s were obtained at baseline from 473 ( 94 % ) men , of whom 378 ( 80 % ) men provided a second sample the following month . Urine was analyzed for 14 monoester metabolites of phthalate diesters by high-performance liquid chromatography coupled to t and em mass spectrometry . Semen sample s were analyzed for 34 quality parameters categorized as general , motility , morphology , sperm head and sperm chromatin structure . MAIN RESULTS AND THE ROLE OF CHANCE Urinary mono-[2-(carboxymethyl ) hexyl ] phthalate ( MCMHP ) , mono-(2-ethyl-5-hydroxyhexyl ) phthalate ( MEHHP ) , mono-benzyl phthalate ( MBzP ) , and mono-isononyl phthalate ( MNP ) were significantly associated with lower total sperm counts and concentrations , larger sperm head sizes , higher proportions of megalo head sperm morphology , and /or other morphological changes . Urinary mono-methyl phthalate ( MMP ) and mono-cyclohexyl phthalate ( MCPP ) were significantly associated with lower sperm motility , and urine mono-2-ethylhexyl phthalate ( MEHP ) was significantly associated with higher sperm motility . LIMITATIONS , REASONS FOR CAUTION While adverse associations were observed , the implication s of the findings for couple fecundity and fertility remain to be established . Cautious interpretation is needed in light of reliance on a single measurement of phthalate measure and no correction for multiple comparisons Objectives Considerable interest and controversy over a possible decline in semen quality during the 20th century raised concern that semen quality could have reached a critically low level where it might affect human reproduction . The authors therefore initiated a study to assess reproductive health in men from the general population and to monitor changes in semen quality over time . Design Cross-sectional study of men from the general Danish population . Inclusion criteria were place of residence in the Copenhagen area , and both the man and his mother being born and raised in Denmark . Men with severe or chronic diseases were not included . Setting Danish one-centre study . Participants 4867 men , median age 19 years , included from 1996 to 2010 . Outcome measures Semen volume , sperm concentration , total sperm count , sperm motility and sperm morphology . Results Only 23 % of participants had optimal sperm concentration and sperm morphology . Comparing with historic data of men attending a Copenhagen infertility clinic in the 1940s and men who recently became fathers , these two groups had significantly better semen quality than our study group from the general population . Over the 15 years , median sperm concentration increased from 43 to 48 million/ml ( p=0.02 ) and total sperm count from 132 to 151 million ( p=0.001 ) . The median percentage of motile spermatozoa and abnormal spermatozoa were 68 % and 93 % , and did not change during the study period . Conclusions This large prospect i ve study of semen quality among young men of the general population showed an increasing trend in sperm concentration and total sperm count . However , only one in four men had optimal semen quality . In addition , one in four will most likely face a prolonged waiting time to pregnancy if they in the future want to father a child and another 15 % are at risk of the need of fertility treatment . Thus , reduced semen quality seems so frequent that it may impair the fertility rates and further increase the dem and for assisted reproduction Impaired semen quality and testicular cancer may be linked through a testicular dysgenesis syndrome of foetal origin . The incidence of testis cancer has been shown to increase among Finnish men , whereas there is no recent publication describing temporal trends in semen quality . Therefore , we carried out a prospect i ve semen quality study and a registry study of testis cancer incidence among Finnish men to explore recent trends . A total of 858 men were investigated in the semen quality study during 1998–2006 .  Median sperm concentrations were 67 ( 95 % CI 57–80 ) million/mL , 60 ( 51–71 ) and 48 ( 39–60 ) for birth cohorts 1979–81 , 1982–83 and 1987 ; total sperm counts 227 ( 189–272 ) million , 202 ( 170–240 ) and 165 ( 132–207 ) ; total number of morphologically normal spermatozoa 18 ( 14–23 ) million , 15 ( 12–19 ) and 11 ( 8–15 ) . Men aged 10–59 years at the time of diagnosis with testicular cancer during 1954–2008 were included in the registry study , which confirmed the increasing incidence of testicular cancer in recent cohorts . These simultaneous and rapidly occurring adverse trends suggest that the underlying causes are environmental and , as such , preventable . Our findings necessitate not only further surveillance of male reproductive health but also research to detect and remove the underlying factors OBJECTIVE To determine the frequency of sperm cells with fragmented DNA in semen sample s from men with genitourinary infection by Chlamydia trachomatis and Mycoplasma and the influence of antibiotic therapy , using the sperm chromatin dispersion test with the Halosperm kit . DESIGN Prospect i ve study . SETTING University-affiliated reproductive medicine center , medical genetics laboratory , and academic biology center . PATIENT(S ) One hundred forty-three male member of couples attending the and rology infertility center and a group 
    Output:
    
WIDER IMPLICATION S This comprehensive meta-regression analysis reports a significant decline in sperm counts ( as measured by SC and TSC ) between 1973 and 2011 , driven by a 50 - 60 % decline among men unselected by fertility from North America , Europe , Australia and New Zeal and .