Decline In Sperm Concentration Research Articles

Effect of the Lebanese civil war on sperm parameters

To assess the effect of the Lebanese civil war on sperm parameters. Retrospective review of patient records. Males providing semen samples at a university laboratory. Semen samples collected 1985-1989 (during the war) were compared with those obtained 1991-1995 (postwar). Males with or without a history of infertility providing semen samples at a university central laboratory. None. Standard clinical semen analysis. The sperm concentration was significantly lower during the war compared with the postwar period. However, the percentage of abnormal sperm morphology increased in the postwar period. War had no significant effect on volume and motility. Postwar, the percent azospermic and those <10 million remained the same, but there was a shift in the count from the borderline count (11-20 million) to normal (>20 million). There was a significant decline in sperm concentration during the Lebanese civil war. Increased stress level during the war is believed to be one of the main factors leading to this finding.

Does the Number and Size of Veins Ligated at Left-Sided Microsurgical Subinguinal Varicocelectomy Affect Semen Analysis Outcomes?

To determine whether the preoperative and intraoperative findings at unilateral microsurgical subinguinal varicocelectomy are predictive of semen analysis changes postoperatively. We identified 42 men who had undergone left-sided microsurgical subinguinal varicocelectomy at our institution and had at least one semen analysis before and after surgery. The preoperative varicocele grade and number and size of spermatic cord veins ligated were recorded. The veins were defined as small (less than 1.0 mm), medium (1.0 to 3.9 mm), and large (4.0 mm or larger). The generalized estimating equation approach was used to assess whether patient age, varicocele grade, number of small, medium, or large veins ligated, total number of veins ligated, and net diameter of all veins ligated were predictive of repeated measurements of semen analysis outcomes. Increasing patient age was associated with a slight decline in sperm concentration (P = 0.046). The number of veins ligated correlated positively with an increase in total motility (P = 0.017). The repair of grade II varicoceles was associated with a significantly greater increase in normal morphology than did the repair of grade I or III varicoceles (P = 0.004). None of the other variables examined were predictive of semen analysis outcome (P >0.05). The relationship between the preoperative/intraoperative findings and semen analysis outcomes after microsurgical subinguinal varicocelectomy remains unclear.

Spatial distribution of ascidian sperm: two-dimensional patterns and short vs. time-integrated assays

Understanding sperm dispersal patterns in free-spawning marine invertebrates is fun- damental to assessing the likelihood of successful fertilization under a range of biological and physi- cal conditions. Field estimates of sperm dispersal in egg broadcasters have relied on sperm assays that sample short-term sperm availability, and tended to focus on simple patterns of availability with distance along a 1-dimensional transect at a single site. However, sperm are diluted in multiple dimensions, and the decrease in concentration with increasing distance from a sperm source in any single dimension is dependent on the rate of dilution in other dimensions. We used short-term sperm availability assays to evaluate the 2-dimensional distribution of sperm downstream of 2 different pop- ulations of the egg-brooding colonial ascidian Botryllus schlosseri. Female colonies were exposed to water samples collected at various distances and 2 depths. Because many egg brooders that feed on phytoplankton appear to collect sperm throughout an extended period of time, short-term assays of sperm availability may underestimate absolute fertilization. Consequently, at one site we also com- pared fertilization in our short-term assays with time-integrated fertilization levels obtained by deploying colonies in the sampling locations for the entire period of egg viability. Our results indicate that vertical patterns of sperm availability with horizontal distance can vary between sites, suggest- ing that sperm transport patterns will be site-specific and dependent on local flow, and that vertical mixing may cause a more rapid decline in sperm concentration with increasing distance. Our com- parison of instantaneous vs. time-integrated assays suggests that short-term assays may vastly under- estimate actual field fertilization levels in some free-spawners.

Effect of two insecticides and two herbicides on the porcine sperm motility patterns using computer-assisted semen analysis (CASA) in vitro

The recent decline in sperm concentration observed in men has developed over a short period of time, suggesting that it could be the result of environmental factors. The present study has evaluated the effects of insecticides Malathion and Diazinon, and herbicides Atrazine and Fenoxaprop-Ethyl on porcine sperm viability and motility patterns in vitro using the eosin–nigrosin staining and a computer-assisted semen analyzer (CASA), respectively. Malathion and Fenoxaprop-Ethyl exerted more deleterious effects than Diazinon and Atrazine. Progressive sperm motility was strongly affected whereas the effect on sperm viability was less pronounced. This suggests that a reduction of sperm motility is not necessarily the result of sperm death. Since sperm motility is dependent on energy metabolism the mechanism of action of these pesticides might be mediated at the level of the mitochondrion, producing a delay in motility and eventual cell death.

Constant decline in sperm concentration in infertile males in an urban population: experience over 18 years

To investigate semen quality in infertile men from an urban population over an 18-year period. Retrospective study. Andrology clinic at a city university hospital. A total of 9,327 men were referred to the clinic for infertility investigation. After excluding those with azoospermia, 7,780 samples were evaluated. Semen samples were analyzed within half an hour of production using computer-automated semen analysis and phase microscopy. Sperm concentration, morphology, and motility; semen pH and leukocyte concentration; and patient age. The median patient age over the study period was 31.6 years, with an increase from 30.8 years in 1986 to 34.4 years in 2003. The median sperm concentration was 10.25 million/mL for the entire period, with a decline from 27.75 million/mL in 1986 to 4.60 million/mL in 2003. The median proportion of normally shaped spermatozoa was 15%, and the proportion of motile spermatozoa was 21%. The pH increased from 7.4 in 1986 to 7.9 in 2003, and the median leukocyte concentration was 1.50 million/mL. A constant decline in median sperm concentration was found in the infertile men. The reason for this remains unclear, although the high pH and leukocyte concentration indicates the involvement of infection.

Relationship between human semen parameters and deoxyribonucleic acid damage assessed by the neutral comet assay

To explore the association between semen parameters and sperm DNA damage. Cross-sectional. Andrology clinic. Two hundred fifty-seven men undergoing infertility assessment. None. Sperm concentration and motility were measured using computer-assisted sperm analysis; morphology was scored using the strict criteria. The neutral comet assay was used to measure sperm DNA damage. Comet assay parameters included comet extent, percent DNA in the comet tail, and tail distributed moment, an integrated measure of length and intensity. We also scored cells that were too long to measure (>300 microm), which we referred to as cells with high DNA damage. Men older than 35 years had a statistically significant increase in the number of cells with high DNA damage as compared with younger men. In age-adjusted regression analyses, the most consistent associations were found between semen parameters and the number of cells with high DNA damage. For an interquartile range change in the number of cells with high DNA damage, sperm concentration declined 14.2 x 10(6)/mL, motility declined 4.3%, and morphology declined 0.5%. Comet extent and percent DNA in the comet tail were also associated with a decline in sperm concentration and motility, respectively. Although there were associations between semen and comet assay parameters, their magnitudes were weak, suggesting that the comet assay provides additional independent information on sperm function.

Cigarette smoking is related to a decrease in semen volume in a population of fertile men

Cigarette smoking is very common despite worldwide anti-smoking campaigns. It is considered as one of the causes of sub-fertility in males. It may result in decreased sperm concentration, poor motility and morphology, and high rates of sperm with DNA damage. However, even though many studies have shown the association of cigarette smoking with reduced semen quality in men diagnosed with infertility, however, studies evaluating the impact of smoking on the semen quality of normal fertile men are lacking. The goal of our study was to evaluate the semen quality and hormonal levels in mild, moderate, heavy and nonsmokers fertile men undergoing vasectomy for sterilization purposes. Retrospective study at a tertiary care institution. University based center. The Institutional Review Board approved the study and all the patients provided informed consent. 889 vasectomies for voluntary sterilization purposes were performed from January 1999 to March 2003. Computer-assisted semen analysis was performed on all specimens, with a Motion Analysis (VP 50) semen analyzer. We divided the patients into four groups: non-smokers (Group A; n = 522), mild smokers (Group B, < − 10 cigarettes/day; n = 143), moderate smokers (Group C, − 11–20 cigarettes/day; n = 154), and heavy smokers (Group D, > − 20 cigarettes/day; n = 70). We evaluated sperm concentration, motility, motion parameters, and hormonal levels in these men at the time of their visit. Data was evaluated with ANOVA. No differences were seen across Groups A to D in sperm concentration (109.18 ± 76.21, 107.49 ± 86.62, 124.51 ± 87.3, and 118.41 ± 85.21; P = 0.071), motility (60.35 ± 15.67, 59.8 ± 15.79, 60.82 ± 14.42, and 53.9 ± 13.18; P = 0.678), follicle-stimulating hormone (3.67 ± 2.10, 4.021 ± 2.10, 3.40 ± 2.4, and 3.53 ± 1.57; P = 0.562), luteinizing hormone (3.32 ± 1.6, 3.66 ± 4.02, 3.03 ± 1.57, and 2.63 ± 1.17; P = 0.213), and serum total testosterone (558.59 ± 178.4, 595.26 ± 175.33, 561.23 ± 166.62, and 659.92 ± 212.67; P = 0.266). Also, sperm motion characteristics did not differ across the groups: curvilinear velocity (71.99 ± 16.44, 71.008 ± 16.37, 72.81 ± 14.41, and 70.2 ± 13.38; P = 0.828), linear velocity (40.58 ± 10.33, 39.43 ± 10.72, 39.60 ± 9.752, and 38.85 ± 7.50; P = 0.796), linearity (55.72 ± 7.86, 54.82 ± 8.73, 53.4 ± 9.16, and 54.63 ± 8.38; P = 0.211), lateral head displacement (3.03 ± 0.92, 3.1 ± 0.88, 3.28 ± 0.99, and 3.001 ± 0.94; P = 0.473), and beat cross frequency (23.79 ± 6.48, 24.01 ± 4.96, 23.47 ± 7.28, and 21.74 ± 7.96; P = 0.499). Semen volume was the only semen parameter, which tends to decrease according to the number of cigarettes smoked (2.82 ± 1.44, 2.42 ± 1.403, 2.30 ± 1.151, and 2.08 ± 0.82; P = 0.004). Semen volume tends to decrease according to the number of cigarettes smoked. A decrease in semen volume may be the first sign of semen quality impairment in cigarette smokers even before a decline in sperm concentration, percent sperm motility and normal sperm morphology.

How would a decline in sperm concentration over time influence the probability of pregnancy?

Reports have suggested a decline in sperm concentration during the second half of the 20th century. The effect of this decline on fecundability (the monthly probability of pregnancy) could be detected in principle by a study of time to pregnancy. In practice, the amplitude of this expected effect is not well known and the statistical power of time-to-pregnancy studies to detect it has not been explored. We developed a nonparametric model to describe a temporal decline in sperm concentration using data on French semen donors. We then applied this model to 419 Danish couples planning a first pregnancy in 1992, to predict their time to pregnancy as if the pregnancy attempt had begun during earlier decades with higher sperm concentrations. Finally, we used bootstrap simulations to estimate the statistical power of prospective or retrospective studies that compared fecundability (estimated from time to pregnancy) across these time periods. We express the change in fecundability over time as a fecundability ratio (FR), with values less than 1 indicating decreased fecundability. We estimate that the median sperm concentration decreased by 21% from 1977 to 1992 and by 47% from 1947 to 1992. The estimated decline in fecundability with those semen changes was 7% from 1977 to 1992 (FR = 0.93, adjusted) and 15% from 1947 to 1992 (FR = 0.85, adjusted). The total numbers of couples that would be needed in prospective studies of time to pregnancy to detect these changes in fecundability (with a power of 80%) were 12,000 when comparing 1977 to 1992, and 2000 when comparing 1947 to 1992. Retrospective studies of the same size that excluded childless couples had much lower statistical power and were biased toward the null. The effect of realistic declines in sperm concentration on time to pregnancy may be observed only with studies that include several thousand couples.

HOW WOULD A TEMPORAL DECLINE IN SPERM CONCENTRATION INFLUENCE THE PROBABILITY OF PREGNANCY? A SIMULATION STUDY FOR THE PERIOD 1947-1992

ISEE-483 Introduction: A decline in sperm concentration was reported during the second half of the twentieth century. Our aim was to simulate its influence on time to pregnancy (TTP), the number of noncontraceptive and sexually active cycles without the occurrence of a pregnancy. Methods: Using data on French semen donors, we defined a nonparametric model corresponding to a temporal decline in sperm concentration. We applied it to 419 Danish couples planning a first pregnancy in 1992, to predict their TTP as if the pregnancy attempt had begun 15 to 45 years earlier. We estimated by bootstrap simulations the statistical power of prospective or retrospective studies comparing TTP over time, assuming that the comparison was done with a discrete Cox model. Results: According to our model, the median sperm concentration decreased by 21% in the 1977-1992 period and by 47% between 1947 and 1992. The number of couples without a pregnancy in six menstrual cycles consequently increased from 151 in 1977 to 159 in 1992 (+5%, adjusted fecundability ratio, FR, 0.93). It increased by 11% between 1947 and 1992 (FR, 0.85). The total numbers of couples who should have been included in prospective TTP studies to detect a FR significantly smaller than 1 with a power of 80% were 12,000 when comparing 1977 to 1992, and 2,000 when comparing 1947 to 1992. Retrospective studies excluding childless couples had, with the same size, statistical powers of about 50% and yielded estimates of the FR biased towards 1, compared to prospective studies. Conclusion: The effect on TTP of realistic declines in sperm concentration may only be observed by TTP studies including several thousand couples. We show for the first time that retrospective TTP studies excluding couples remaining childless appear to have a smaller statistical power than prospective studies and may underestimate the effect of the exposure of interest on fecundability.

Impact of therapy and androgen receptor polymorphism on sperm concentration in men treated for testicular germ cell cancer: a longitudinal study.

Testicular cancer (TC) patients have a high survival rate, and the question of post-therapy recovery of sperm production and its dependence on genetic predisposition is of major interest. Ejaculates were obtained from 112 TC patients at one or more of the following time points: post-orchidectomy, or 6, 12, 24, 36 and 60 months post-therapy. The lengths of the androgen receptor (AR) function modulating CAG and GGN repeats in leukocyte DNA were also analysed. No significant decrease in sperm concentration was seen in men who received 1-2 cycles of adjuvant chemotherapy (ACT). Radiotherapy (RT) or more than two cycles of chemotherapy (HCT) caused an initial decline in sperm concentration, which returned to pre-treatment levels 2-5 years after therapy. In the HCT group, sperm concentration 12-24 months post-treatment (T(12-24)) was inversely correlated with CAG length (rho = -0.72, P = 0.03). The type of treatment, but not the concentration at T(0), was an independent predictor of sperm concentration at T(6) (P < 0.0005) and T(12-24) (P = 0.004). ACT did not induce a significant decline in sperm concentration. After HCT and RT, a significant reduction of sperm concentration was observed, recovering to pre-treatment levels 2-5 years post-treatment. In HCT-treated patients, the AR CAG length influenced the recovery of spermatogenesis.

Estrogens and health in males

Estrogen receptor concentrations are higher in the male reproductive tract than in other organs. Brain structure, neuronal organization and behavioral sex differences result from brain conversion of testosterone into estradiol within the brain. Estrogens modulate hormonal secretion at pituitary level and immune function at thymus level. Estrogens promote vasodilatatory and protective effects on the cardiovascular system by acting on the vascular smooth muscle and endothelium. Adult men with mutations in genes for estrogen receptor or aromatase are affected by osteopenia and tall stature, open epiphysis, which is corrected by estrogen treatment. Over the past few years there has seen a decline in sperm concentration, which has been attributed to exposure of fetal testes to estrogens. Many substances have estrogen-like properties and inhibit the action of estradiol or testosterone action. In conclusion, estrogens play a pivotal role in men also. In particular, taking in account their prevalent origin from testosterone aromatization at tissue and peripheral levels the presence and the distribution of the two receptors (ERα and ERβ) are responsible for different responses in physiological and pathological conditions.

Is the human testis still an organ at risk?

Although several lines of circumstantial evidence suggest that we may be seeing adverse changes in male reproductive health, it is the possibility that semen quality may have declined that has attracted most attention. In a meta-analysis Carlsen et al examined data from 61 papers published between 1938 and 1991 on the quality of semen in normal men.1 Using linear regression analysis, they identified statistically significant decreases over time in mean ejaculate volume and a fall in sperm concentration from 113x106/ml in 1940 to 66x106/ml in 1990. This report has aroused continuing debate.2 Subsequently, Auger et al published data on 1351 healthy fertile candidates for sperm donation who attended one centre between 1973 and 1992.3 Correcting for sexual abstinence, they observed a significant decline in sperm concentration, the percentage of motile spermatozoa, and the percentage of morphologically normal spermatozoa both as a function of year of birth and age at donation. Several workers have since …

Synergistic effects of Aroclor 1254 and mirex on the semen characteristics of American Kestrels.

Semen characteristics of captive American Kestrels (Falco sparverius) fed 8 ppm mirex or 33 ppm Aroclor® 1254, singly or in combination, were compared to a control group. Aroclor® 1254 produced a decline in sperm concentration but no compensatory increase in semen volume, resulting in a 22–27% decrease in sperm numbers per ejaculate. Mirex produced a marked decline in sperm concentration with a slight compensatory increase in semen volume resulting in a 70% decrease in sperm numbers. The combination of Aroclor® 1254 and mirex, at the same concentrations as fed singly, decreased sperm concentration to the same level as the Aroclor® alone with a 73% increase in semen volume, resulting in sperm numbers which did not differ from those of the controls. No effect on sperm motility was observed for any contaminant. Temporal patterns in semen characteristics differed. There was a highly significant interaction effect between Aroclor® 1254 and mirex. The excretion of mirex was increased in the presence of Aroclor® 1254, and the combination diet reduced the relative concentration of Aroclor® in the testes. The testicular mass of the PCBs + mirex group was increased. The results suggest that migratory flesheating birds feeding on a PCB- or mirex-contaminated food chain could consume enough toxicant to alter their semen quality in that breeding season, which, when coupled with altered courtship, could reduce the fertility of eggs and the reproductive fitness of the individual.