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Background: Numerous studies have reported declines in semen quality and other markers of male reproductive health. Our previous meta-analysis reported a significant decrease in sperm concentration (SC) and total sperm count (TSC) among men from North America-Europe-Australia (NEA) based on studies published during 1981-2013. At that time, there were too few studies with data from South/Central America-Asia-Africa (SAA) to reliably estimate trends among men from these continents., Objective and Rationale: The aim of this study was to examine trends in sperm count among men from all continents. The broader implications of a global decline in sperm count, the knowledge gaps left unfilled by our prior analysis and the controversies surrounding this issue warranted an up-to-date meta-analysis., Search Methods: We searched PubMed/MEDLINE and EMBASE to identify studies of human SC and TSC published during 2014-2019. After review of 2936 abstracts and 868 full articles, 44 estimates of SC and TSC from 38 studies met the protocol criteria. Data were extracted on semen parameters (SC, TSC, semen volume), collection year and covariates. Combining these new data with data from our previous meta-analysis, the current meta-analysis includes results from 223 studies, yielding 288 estimates based on semen samples collected 1973-2018. Slopes of SC and TSC were estimated as functions of sample collection year using simple linear regression as well as weighted meta-regression. The latter models were adjusted for predetermined covariates and examined for modification by fertility status (unselected by fertility versus fertile), and by two groups of continents: NEA and SAA. These analyses were repeated for data collected post-2000. Multiple sensitivity analyses were conducted to examine assumptions, including linearity., Outcomes: Overall, SC declined appreciably between 1973 and 2018 (slope in the simple linear model: -0.87 million/ml/year, 95% CI: -0.89 to -0.86; P < 0.001). In an adjusted meta-regression model, which included two interaction terms [time × fertility group (P = 0.012) and time × continents (P = 0.058)], declines were seen among unselected men from NEA (-1.27; -1.78 to -0.77; P < 0.001) and unselected men from SAA (-0.65; -1.29 to -0.01; P = 0.045) and fertile men from NEA (-0.50; -1.00 to -0.01; P = 0.046). Among unselected men from all continents, the mean SC declined by 51.6% between 1973 and 2018 (-1.17: -1.66 to -0.68; P < 0.001). The slope for SC among unselected men was steeper in a model restricted to post-2000 data (-1.73: -3.23 to -0.24; P = 0.024) and the percent decline per year doubled, increasing from 1.16% post-1972 to 2.64% post-2000. Results were similar for TSC, with a 62.3% overall decline among unselected men (-4.70 million/year; -6.56 to -2.83; P < 0.001) in the adjusted meta-regression model. All results changed only minimally in multiple sensitivity analyses., Wider Implications: This analysis is the first to report a decline in sperm count among unselected men from South/Central America-Asia-Africa, in contrast to our previous meta-analysis that was underpowered to examine those continents. Furthermore, data suggest that this world-wide decline is continuing in the 21st century at an accelerated pace. Research on the causes of this continuing decline and actions to prevent further disruption of male reproductive health are urgently needed., (© The Author(s) 2022. Published by Oxford University Press on behalf of European Society of Human Reproduction and Embryology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Although varicoceles are a widely accepted identifiable male factor in infertile couples, the benefit of varicocele repair in improving pregnancy and live birth rates remains uncertain. The Study for Future Families obtained semen and reproductive hormone samples from US men whose partners were currently pregnant. In our analysis cohort of 709 men, a varicocele was detected by clinical examination in 56 (8%) of men. Men with varicocele had smaller left testis, and lower total and total motile sperm counts than men without varicocele. Gonadotropin levels were higher as well in men with varicocele. Interestingly, testosterone levels were also slightly higher in men with varicocele. Despite these differences, there was no difference between the groups in the time to achieve the study pregnancy or percentage of men with a previous pregnancy. We conclude that even in fertile men, varicoceles are associated with some degree of testicular hypofunction. This would support current recommendations to consider varicocele repair in male partners in infertile couples who demonstrate both a varicocele and abnormal semen parameters and after evaluation for treatable female factors., (© 2019 Blackwell Verlag GmbH.)

Background: Benzophenone (BP)-type ultraviolet (UV) light filters are chemicals frequently added to personal care products, insect repellents, sunscreens, and beverage and food packaging to diminish the harmful effects of UV sunlight on human skin or foodstuffs. BP-type UV filters have shown negative effects on male reproduction function in in vitro and animal models, but human epidemiologic studies are limited. The goal of this study was to examine associations between urinary concentrations of BP-type UV filters and semen quality and reproductive hormone levels., Methods: This is a cross-sectional study with 215 young university students (18-23 years old) recruited between 2010 and 2011 in Southern Spain (Murcia Region). All men provided a urine, blood and semen sample on a single day. Urinary concentrations of 2,4-dihydroxybenzophenone (BP-1); 2,2',4,4'-tetrahydroxybenzophenone (BP-2); 2-hydroxy-4-methoxybenzophenone (BP-3); 2,2'-dihydroxy-4-methoxybenzophenone (BP-8) and 4-hydroxybenzophenone (4OH-BP) were measured by dispersive liquid-liquid microextraction and ultra-high performance liquid chromatography with tandem mass spectrometry detection. Semen quality was evaluated by measuring volume, sperm counts, motility and morphology. Serum samples were analyzed for reproductive hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), testosterone (T), inhibin B and estradiol (E2). Associations between urinary concentrations of BP-type UV filters and semen quality parameters and reproductive hormone levels were examined using linear regression, adjusting for potential confounders., Results: Ninety-seven percent of the men had detectable urinary concentrations of at least one of the five BP-type UV filters quantified. After adjustment for important covariates (body mass index, smoking status and time of blood sample collection), there was a significant positive association between urinary BP-1 and BP-3 concentrations and serum FSH levels (β = 0.08, 95%CI: 0.009; 0.15 and β = 0.04, 95%CI: 0.0002; 0.08, respectively). Urinary BP-1 concentration was also significantly positively associated with T/E2 (β = 0.04, 95%CI: 0.002; 0.07) and negatively with inhibin b/FSH (β = -0.11, 95%CI: -0.21; -0.006) ratio. No significant associations were found between other urinary BP-type UV filters and other reproductive hormone levels or between any semen parameters and any of the urinary BP-type UV filters quantified., Conclusions: Our results suggest that, in young men, urinary BP-type UV filters may be associated with a modest alteration of some reproductive hormones, but the effects we report on reproductive function are likely to be small, and of unclear clinical significance. Further research is needed to replicate these findings in other male populations., (Copyright © 2018 Elsevier GmbH. All rights reserved.)

Background: Numerous studies have shown that occupational or environmental pesticide exposure can affect male fertility. There is less evidence, however, regarding any potentially adverse effects of pesticide residues in foods on markers of male fertility potential., Objectives: We examined the relations between fruit and vegetable intake, considering pesticide residue status, and semen quality and serum concentrations of reproductive hormones in healthy young men., Methods: The Rochester Young Men's Study is a cross-sectional study that recruited men aged 18-22 y (n = 189) in Rochester, New York. Participants completed a questionnaire, provided a semen sample, had a blood sample drawn, and underwent a physical examination at enrollment. Semen samples were analyzed for total sperm count, sperm concentration, morphology, motility, ejaculate volume, total motile count, and total normal count. Dietary intake during the previous year was assessed by a validated food-frequency questionnaire. Fruit and vegetables were categorized as having high [Pesticide Residue Burden Score (PRBS) ≥4] or low-to-moderate (PRBS <4) pesticide residues on the basis of data from the USDA Pesticide Data Program. Linear regression models were used to analyze the associations of fruit and vegetable intake with semen variables and reproductive hormones while adjusting for potential confounding factors., Results: The total intake of fruit and vegetables was unrelated to semen quality. However, the intake of fruit and vegetables with low-to-moderate pesticide residues was associated with a higher total sperm count and sperm concentration, whereas the intake of fruit and vegetables with high pesticide residues was unrelated to semen quality. On average, men in the highest quartile of low-to-moderate-pesticide fruit and vegetable intake (≥2.8 servings/d) had a 169% (95% CI: 45%, 400%) higher total sperm count and a 173% (95% CI: 57%, 375%) higher sperm concentration than did men in the lowest quartile (<1.1 servings/d; P-trend = 0.003 and 0.0005, respectively). The intake of fruit and vegetables, regardless of pesticide-residue status, was not associated with reproductive hormone concentrations., Conclusions: The consumption of fruit and vegetables with low-to-moderate pesticide residues was positively related to sperm counts in young men unselected by fertility status. This suggests that pesticide residues may modify the beneficial effects of fruit and vegetable intake on semen quality., (© 2016 American Society for Nutrition.)

Objective: To assess the relationship between dietary antioxidant intake and semen quality in young healthy males., Design: Cross-sectional study., Setting: University and college campuses in the Rochester, New York, area., Patient(s): One hundred eighty-nine university-aged men., Intervention(s): None., Main Outcome Measure(s): Semen volume, total sperm count, concentration, motility, total motile count, and morphology., Result(s): Progressive motility was 6.5 (95% confidence interval [CI], 0.6, 12.3) percentage units higher among men in the highest quartile of β-carotene intake compared with men in the lowest quartile. Similar results were observed for lutein intake. Lycopene intake was positively related to sperm morphology. The adjusted percentages (95% CI) of morphologically normal sperm in increasing quartiles of lycopene intake were 8.0 (6.7, 9.3), 7.7 (6.4, 9.0), 9.2 (7.9, 10.5), and 9.7 (8.4, 11.0). There was a nonlinear relationship between vitamin C intake and sperm concentration, with men in the second quartile of intake having, on average, the highest sperm concentrations and men in the top quartile of intake having the lowest concentrations., Conclusion(s): In a population of healthy young men, carotenoid intake was associated with higher sperm motility and, in the case of lycopene, better sperm morphology. Our data suggest that dietary carotenoids may have a positive impact on semen quality., (Copyright © 2013 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.)

Background: Rodent and in vitro studies have demonstrated the estrogenicity of bisphenol A (BPA). However, few studies have examined the relationship between human exposure to BPA and male reproductive function., Objectives: We investigated the relationships between environmental BPA exposure and reproductive parameters, including semen quality and male reproductive hormones, in prospectively recruited fertile men., Methods: Participants (n = 375) were partners of pregnant women who participated in the Study for Future Families in four U.S. cities, and all of the men provided blood, semen, and urine samples. BPA was measured in urine. Serum samples were analyzed for reproductive hormones, including follicle-stimulating hormone, luteinizing hormone (LH), testosterone, inhibin B, estradiol, and sex hormone-binding globulin (SHBG), as well as the free androgen index (FAI). Semen analyses were performed according to World Health Organization criteria. Pearson correlations were used for unadjusted analyses, and multiple linear regression analyses were used to examine associations controlling for age, body mass index, smoking, ethnicity, urinary creatinine concentration, time of sample collection, and duration of abstinence., Results: After multivariate adjustment, we observed no significant associations between any semen parameter and urinary BPA concentration. However, a significant inverse association was found between urinary BPA concentration and FAI levels and the FAI/LH ratio, as well as a significant positive association between BPA and SHBG., Conclusions: Our results suggest that, in fertile men, exposure to low environmental levels of BPA may be associated with a modest reduction in markers of free testosterone, but any effects on reproductive function are likely to be small, and of uncertain clinical significance.

The authors examined the association between semen quality and caffeine intake among 2,554 young Danish men recruited when they were examined to determine their fitness for military service in 2001-2005. The men delivered a semen sample and answered a questionnaire including information about caffeine intake from various sources, from which total caffeine intake was calculated. Moderate caffeine and cola intakes (101-800 mg/day and < or =14 0.5-L bottles of cola/week) compared with low intake (< or =100 mg/day, no cola intake) were not associated with semen quality. High cola (>14 0.5-L bottles/week) and/or caffeine (>800 mg/day) intake was associated with reduced sperm concentration and total sperm count, although only significant for cola. High-intake cola drinkers had an adjusted sperm concentration and total sperm count of 40 mill/mL (95% confidence interval (CI): 32, 51) and 121 mill (95% CI: 92, 160), respectively, compared with 56 mill/mL (95% CI: 50, 64) and 181 mill (95% CI: 156, 210) in non-cola-drinkers, which could not be attributed to the caffeine they consumed because it was <140 mg/day. Therefore, the authors cannot exclude the possibility of a threshold above which cola, and possibly caffeine, negatively affects semen quality. Alternatively, the less healthy lifestyle of these men may explain these findings.

We conducted the first US study to compare semen quality among study centres using standardized methods and strict quality control. We present data on semen quality in partners of 493 pregnant women recruited through prenatal clinics in four US cities during 1999-2001. Sperm concentration, semen volume and motility were determined at the centres and morphology was assessed at a central laboratory. While between-centre differences in sperm morphology and sample volume were small, sperm concentration and motility were significantly reduced in Columbia, MO (MO) relative to men in New York, NY, Minneapolis, MN and Los Angeles, CA; total number of motile sperm was 113 x 10(6) in MO and 162, 201 and 196 x 10(6) in CA, MN and NY respectively. Differences among centres remained significant in multivariate models that controlled for abstinence time, semen analysis time, age, race, smoking, history of sexually transmitted disease and recent fever (all p-values <0.01). We hypothesized that poorer sperm concentration and motility in MO men relative to other centres might be related to agricultural pesticides that are commonly used in the mid-west. We investigated this hypothesis by conducting a nested case-control study within the MO cohort. We selected 25 men in this cohort for whom all semen parameters (concentration, % normal morphology and % motile) were low as cases and an equal number of men for whom all semen parameters were within normal limits as controls. We measured metabolites of eight non-persistent, current-use pesticides in urine samples the men had provided at the time of semen collection. Pesticide metabolite levels were elevated in cases compared with controls for the herbicides alachlor and atrazine, and for the insecticide diazinon (2-isopropoxy-4-methyl-pyrimidinol) (p-values for Wilcoxon rank test = 0.0007, 0.012, and 0.0004 for alachlor, atrazine and diazinon respectively). Men with higher levels of alachlor or diazinon were significantly more likely to be cases than men with low levels [odds ratios (OR) = 30.0, 16.7 for alachlor and diazinon respectively], as were men with atrazine over the limit of detection (OR = 11.3). These associations between current-use pesticides and reduced semen quality suggest that agricultural chemicals may have contributed to the reduced semen quality seen in fertile men from mid-Missouri.

Background: Several recent studies have reported low sperm concentration in young men recruited from the general population, but it is unknown whether the semen quality of these young men reflects that of more mature men or is reduced due to relative immaturity. We conducted a longitudinal follow-up study to address this question., Methods: We followed 158 young men (median age = 19.1 years at entry) for up to 4 years and requested quarterly semen samples (total 1838 semen samples) and yearly genital examinations. We examined longitudinal changes in sperm concentration, semen volume, percentage of immotile sperm and percentage of morphologically normal sperm. We used general linear models in which each man served as his own control which also controlled for age, smoking, urogenital infections or disorders, fever and abstinence time., Results: We found no evidence that sperm concentration, total sperm count or percentage of morphologically normal sperm changed appreciably during the 4 years of follow-up. Semen volume appeared to increase slightly with age, perhaps due to greater acceptance of the study protocol by participants. Sperm motility also improved somewhat, although this may, at least in part, reflect a trend in motility measurement., Conclusions: In this analysis of 1838 semen samples from 158 young men from the Copenhagen area, sperm concentration, total sperm count and sperm morphology did not change significantly during 4 years of follow-up, suggesting that previously reported low sperm concentration and poor sperm morphology among young Danish men are unlikely to be the result of immaturity.

Rigorously standardized laboratory protocols and strict quality control (QC) are essential for meaningful comparisons between semen quality data from multiple sites. We describe our experience with the Study for Future Families (SFF), a multicenter study of semen quality in the United States. Detailed protocols were developed, and technicians from each study site attended a training session at the central laboratory. Technicians received blinded replicates from diluted semen specimens for counting by MicroCell and hemacytometer. Sperm motility was assessed using videotaped recordings for simple percent motility and categorical assessment of individual sperm progression as recommended by the World Health Organization (WHO). The mean intertechnician coefficient of variation for individual specimens was 12.6% for MicroCell counts, 15.2% for hemacytometer counts, and 10.5% for percent motility. Intratechnician coefficients of variation averaged 10.3% for MicroCell counts, 12.5% for hemacytometer counts, and 5.2% for percent motility. The average percent differences between the technicians' values and the central standard for individual specimens were 13.5%, 16.6%, and 11.9% for MicroCell counts, hemacytometer counts, and simple percent motility, respectively. We achieved our goal of maintaining mean intratechnician coefficients of variation and mean percent differences from the standard values of 15% or less for measurements of simple percent motility and sperm concentration by MicroCell. Standardization using the Improved Neubauer hemacytometer chamber proved more difficult. We were not successful in standardizing a method for categorical assessment of individual sperm progression.

Semen evaluation methodology is complex and difficult to standardize. Rigorously standardized laboratory protocols and strict quality control (QC) are essential for meaningful comparison of data from multiple sites. We describe the methods used for determination of semen volume, sperm concentration, and percent sperm motility in the Study for Future Families, a multicenter study of semen quality in the United States. Each of these 3 semen parameters was assessed using 2 techniques, which provided the opportunity to compare precision and assess suitability for multicenter studies. Detailed protocols were used, and technicians were centrally trained. A total of 509 semen evaluations were performed. Semen volume measured by weight was greater (P <.0001) than that determined by pipetting (3.7 +/- 1.6 mL vs 3.2 +/- 1.6 mL). Sperm concentration determined using hemacytometer chambers was consistently higher (P <.001) than that using disposable MicroCell chambers (81.0 x 10(6)/mL vs 65.9 x 10(6)/mL). Precision was slightly greater for the MicroCell chamber. The percentage of motile sperm was assessed by a simple counting technique as well as by the World Health Organization categorical method that assigns individual motile sperm to "a," "b," and "c" categories on the basis of progression. When these 3 categories were collapsed, the methods provided values that were not statistically different (P >.05), although the collapsed values tended to be higher (58.1% vs 51.6%) and less precise (CV 7.7% vs 4.1%) for the categorical method than for motility determined using the simple method. The data obtained in this study demonstrate the critical need for rigorous standardization of protocols and techniques for multicenter studies.

Background: Trihalomethanes (THMs) are byproducts of drinking water chlorination whose effects on semen quality have not been previously studied in humans., Methods: We examined the relationship of THMs to semen quality in 157 healthy men from couples without known risk factors for infertility. Total THM (TTHM) levels were assigned based on water utility measurements taken during the 90 days preceding semen collection. We analyzed continuous semen parameters in relation to total and individual THMs, adjusting for potential confounders by using repeated measures analyses., Results: TTHM level was not associated with decrements in semen quality. Percent normal morphology decreased and percent head defects increased at higher levels of an ingestion metric (TTHM multiplied by cold home tap water consumption). At the highest level of the ingestion metric (>160 mug/L x glasses/day, which is equivalent to >2 glasses/day of water containing 80 mug/L) we observed a difference of -7.1 (95% confidence interval = -12.7 to -1.6) for percent morphologically normal sperm compared with the lowest level (

We previously reported reduced sperm concentration and motility in fertile men in a U.S. agrarian area (Columbia, MO) relative to men from U.S. urban centers (Minneapolis, MN; Los Angeles, CA; New York, NY). In the present study we address the hypothesis that pesticides currently used in agriculture in the Midwest contributed to these differences in semen quality. We selected men in whom all semen parameters (concentration, percentage sperm with normal morphology, and percentage motile sperm) were low (cases) and men in whom all semen parameters were within normal limits (controls) within Missouri and Minnesota (sample sizes of 50 and 36, respectively) and measured metabolites of eight current-use pesticides in urine samples provided at the time of semen collection. All pesticide analyses were conducted blind with respect to center and case-control status. Pesticide metabolite levels were elevated in Missouri cases, compared with controls, for the herbicides alachlor and atrazine and for the insecticide diazinon [2-isopropoxy-4-methyl-pyrimidinol (IMPY)]; for Wilcoxon rank test, p = 0.0007, 0.012, and 0.0004 for alachlor, atrazine, and IMPY, respectively. Men from Missouri with high levels of alachlor or IMPY were significantly more likely to be cases than were men with low levels [odds ratios (ORs) = 30.0 and 16.7 for alachlor and IMPY, respectively], as were men with atrazine levels higher than the limit of detection (OR = 11.3). The herbicides 2,4-D (2,4-dichlorophenoxyacetic acid) and metolachlor were also associated with poor semen quality in some analyses, whereas acetochlor levels were lower in cases than in controls (p = 0.04). No significant associations were seen for any pesticides within Minnesota, where levels of agricultural pesticides were low, or for the insect repellent DEET (N,N-diethyl-m-toluamide) or the malathion metabolite malathion dicarboxylic acid. These associations between current-use pesticides and reduced semen quality suggest that agricultural chemicals may have contributed to the reduction in semen quality in fertile men from mid-Missouri we reported previously.

Although geographic variation in semen quality has been reported, this is the first study in the United States to compare semen quality among study centers using standardized methods and strict quality control. We evaluated semen specimens from partners of 512 pregnant women recruited through prenatal clinics in four U.S. cities during 1999-2001; 91% of men provided two specimens. Sperm concentration, semen volume, and motility were determined at the centers, and morphology was assessed at a central laboratory. Study protocols were identical across centers, and quality control was rigorously maintained. Sperm concentration was significantly lower in Columbia, Missouri, than in New York, New York; Minneapolis, Minnesota; and Los Angeles, California. Mean counts were 58.7, 102.9, 98.6, and 80.8 X 10(6)/mL (medians 53.5, 88.5, 81.8, and 64.8 X 10(6)/mL) in Missouri, New York, Minnesota, and California, respectively. The total number of motile sperm was also lower in Missouri than in other centers: 113, 196, 201, and 162 X 10(6) in Missouri, New York, Minnesota, and California, respectively. Semen volume and the percent morphologically normal sperm did not differ appreciably among centers. These between-center differences remained significant in multivariate models that controlled for abstinence time, semen analysis time, age, race, smoking, history of sexually transmitted disease, and recent fever (all p-values < 0.01). Confounding factors and differences in study methods are unlikely to account for the lower semen quality seen in this mid-Missouri population. These data suggest that sperm concentration and motility may be reduced in semirural and agricultural areas relative to more urban and less agriculturally exposed areas.

Background: Numerous studies have shown that occupational or environmental pesticide exposure can affect male fertility. There is less evidence, however, regarding any potentially adverse effects of pesticide residues in foods on markers of male fertility potential.Objectives: We examined the relations between fruit and vegetable intake, considering pesticide residue status, and semen quality and serum concentrations of reproductive hormones in healthy young men.Methods: The Rochester Young Men's Study is a cross-sectional study that recruited men aged 18-22 y (n = 189) in Rochester, New York. Participants completed a questionnaire, provided a semen sample, had a blood sample drawn, and underwent a physical examination at enrollment. Semen samples were analyzed for total sperm count, sperm concentration, morphology, motility, ejaculate volume, total motile count, and total normal count. Dietary intake during the previous year was assessed by a validated food-frequency questionnaire. Fruit and vegetables were categorized as having high [Pesticide Residue Burden Score (PRBS) ≥4] or low-to-moderate (PRBS <4) pesticide residues on the basis of data from the USDA Pesticide Data Program. Linear regression models were used to analyze the associations of fruit and vegetable intake with semen variables and reproductive hormones while adjusting for potential confounding factors.Results: The total intake of fruit and vegetables was unrelated to semen quality. However, the intake of fruit and vegetables with low-to-moderate pesticide residues was associated with a higher total sperm count and sperm concentration, whereas the intake of fruit and vegetables with high pesticide residues was unrelated to semen quality. On average, men in the highest quartile of low-to-moderate-pesticide fruit and vegetable intake (≥2.8 servings/d) had a 169% (95% CI: 45%, 400%) higher total sperm count and a 173% (95% CI: 57%, 375%) higher sperm concentration than did men in the lowest quartile (<1.1 servings/d; P-trend = 0.003 and 0.0005, respectively). The intake of fruit and vegetables, regardless of pesticide-residue status, was not associated with reproductive hormone concentrations.Conclusions: The consumption of fruit and vegetables with low-to-moderate pesticide residues was positively related to sperm counts in young men unselected by fertility status. This suggests that pesticide residues may modify the beneficial effects of fruit and vegetable intake on semen quality. [ABSTRACT FROM AUTHOR]

Presents information on a study regarding the factors that cause the decrease of sperm count and density of vertebrates. Details on the measurement error of semen analysis method; Variability of sperm density; Effect of inappropriate statistical models.

A response by S. H. Swan and colleagues to a letter to the editor about their article "Semen Quality of Fertile US Males in Relation to Their Mother's Beef Consumption During Pregnancy," published in the 2007 issue is presented.

Objective: To examine the association between stressful life events and semen parameters. Design: Cross-sectional analysis in a pregnancy cohort study. Setting: Prenatal clinics in five U.S. cities. Patient(s): Fertile men (n = 744) in the Study for Future Families, a cohort study of pregnant women and their partners. Intervention(s): None. Main Outcome Measure(s): Sperm concentration, percent motile, and percent normal morphology and classification above/below World Health Organization (WHO) cutoffs for semen quality. Result(s): After adjusting for confounders, men reporting 2+ recent stressful life events had an increased risk of being classified below WHO thresholds for “normal” defined by concentration, motility, and morphology criteria compared with men reporting <2 stressful life events (odds ratio [OR] = 2.06; 95% confidence interval [CI], 1.18, 3.61; OR = 1.54; 95% CI, 1.04, 2.29; OR = 1.93; 95% CI, 1.02, 3.66 for concentration, motility and morphology, respectively). Men experiencing 2+ stressful life events had lower sperm concentration (log scale, β = −0.25; 95% CI, −0.38, −0.11) and lower percent motile sperm (β = −1.95; 95% CI, −3.98, 0.07), but percent normal morphology was less affected. Conclusion(s): These results suggest that stressful life events may be associated with decreased semen quality in fertile men. The experience of psychosocial stress may be a modifiable factor in the development of idiopathic infertility. [Copyright &y& Elsevier]