Prediction of spontaneous conception based on semen parameters

Accurate prognosis of male fertility based on semen measurements is still not straightforward. This study was designed to identify the best predictors of fertility and to develop a multiple regression model predicting fertility using selected parameters of semen analysis. The predictive value of standard semen parameters and selected functional tests were studied in 113 fertile men and in 109 subfertile men whose spouses had a normal infertility workup. Individual semen parameters were evaluated using the receiver operating characteristic curve. Logistic regression based on linear functions of analysed sperm parameters was used to predict the chance of spontaneous conception. Logistic regression modelling revealed that the best prediction of spontaneous conception was obtained using 12 semen parameters: sperm concentration, total progressive motility (A + B), motility grade C or D, normal sperm morphology, defects of: head, acrosome, midpiece and tail, spontaneous acrosome reaction, hypo-osmotic swelling (HOS) test and acid aniline blue test. This mathematical model reached 90.3% accuracy in predicting in vivo conception and 90.8% for its lack. A satisfactory prediction of male fertility was also obtained using only four semen measurements: sperm concentration, total progressive motility (grade A + B), normal morphology, and HOS test; this model correctly identified as fertile 84.1% of those who conceived and identified as subfertile 88.1% of those who did not achieve pregnancy. In conclusion, basic semen analysis and selected functional tests of sperm provide important information regarding male fertility status.     

Development of normal reference values for seminal reactive oxygen species and their correlation with leukocytes and semen parameters in a fertile population

Although reactive oxygen species (ROSs) are clearly implicated in the pathogenesis of male infertility, few studies have attempted to define the basal levels of ROSs in fertile men. Levels of ROSs are highly influenced by the presence of leukocytes and are associated with decreased seminal parameters. The objective of our study was to determine the normal ROS reference values in neat and washed semen of a fertile population and to correlate the leukocyte concentrations with seminal parameters. We evaluated 114 fertile men seeking vasectomy and 47 subfertile patients as a positive control. All samples were subjected to semen analysis and Endtz testing; chemiluminescence assay was used to determine ROS levels. All seminal parameters were significantly higher in the fertile men than in the subfertile patients. In nonleukocytospermic samples, ROS levels were lower in the fertile men than in the subfertile patients in neat (0.29 [0.18, 0.54] vs 0.94 [0.38, 1.51]) (P = .001) and washed semen (5.73 [1.90, 14.71] vs 23.4 [9.46, 115.55]) (P = .001). Similarly, in samples with leukocytes (Entdz, less than 1 x 10(6)/mL), ROS levels were lower in the fertile men in neat (0.75 [0.27, 1.71] vs 2.0 [0.97, 27.41]) (P = .001) and washed semen (15.85 [4.18, 62.16] vs 239.83 [33.4, 1193.75]) (P < .0001). As expected, samples with leukocytes had significantly higher ROS values in washed and neat semen. In the fertile population, ROSs were positively correlated with leukocytes and negatively correlated with sperm count and motility. In semen samples without leukocytes, the normality cutoff of ROSs was 0.55 x 10(4) counted photons per minute with 76.4% area under the curve (AUC) in the neat samples and 10.0 x 10(4) counted photons per minute with 77% AUC in the washed samples. In semen samples with leukocytes, the cutoff for ROSs in neat samples was 1.25 with 72.7% AUC and 51.5 with 81% AUC in the washed samples. We defined the cutoff levels of ROSs in a fertile population. Seminal leukocyte levels below 1 x 10(6)/mL were associated with increased ROSs. ROS levels were positively correlated with leukocytes and negatively correlated with sperm motility and concentration. Patients with normal seminal parameters and lower seminal leukocyte levels may benefit from therapeutic interventions that improve semen quality.     

Sperm morphology assessment: diagnostic potential and comparitive analysis of strict or WHO criteria in a fertile and a subfertile population

This prospective study compared the diagnostic and predictive potential of sperm morphology assessments in a fertile vs. a subfertile population, evaluated in three different laboratories. The fertile population included 144 men who had recently fertilized their partners. As subfertile controls, 136 men with a history of subfertility for more than 12␣months were used. All semen samples (280) were evaluated in three different centres in a blind fashion, without any patient information. The evaluation of sperm morphology was performed according to the criteria normally used in the different laboratories: WHO (1992) criteria for laboratory A, and Tygerberg strict criteria for laboratories B and C. Using ROC analysis, the predictive power of sperm morphology turned out to be different in the three laboratories (area under ROC curve: 69% for lab A, 72% for lab B and 78% for lab C). Using percentile 10 of the fertile population as the cut-off value for normality, we obtained the following results: 2, 1 and 5% for laboratories A, B and C, respectively. Using ROC analysis cut-off values with optimal specificity and sensitivity were 6, 1 and 10%, respectively.
Although our data highlight a reasonable predictive power of sperm morphology in centres using different or the same criteria, cut-off values for normality were different, even when the same criteria were applied. These results stress the importance of standardization in sperm morphology evaluation and the need for examining a reference population in estimating the real threshold value in different laboratories.     

Use of theophylline to enhance sperm function.

Poor sperm motility is an important factor in male infertility. Preliminary results in our laboratory on a group of 19 men (10 suspected infertile men and 9 fertile donors) showed stimulation of sperm fertilizing ability after sperm washing with theophylline as demonstrated by zona free hamster egg penetration test. The egg penetration rate for the control spermatozoa samples from subfertile men was 16%. Incubation with theophylline (10 mM) increased the penetration rate to 46%, whereas semen incubation with theophylline (20 mM) increased the penetration rate to 51%. A similar twofold increase in egg penetration was observed in the semen of fertile men incubated with theophylline of similar concentrations. Subfertile patients with ejaculate volumes of less than or equal to 1 ml or total motile sperm count of less than or equal to 10 x 10(6)/mL or increased semen viscosity did not exhibit beneficial effects with theophylline washing as measured by hamster egg penetration test score. The increase in percentage of penetrated eggs with theophylline use in both fertile and subfertile men was significant at 10 mM concentration (p less than .001) and 20 mM (p less than .001) when compared to control (untreated) samples. No significant difference in penetration rate was seen between 10 and 20 mM theophylline concentrations. It appears that theophylline may be useful in improving the fertilizing capacity of selected human semen samples with poor motility and poor penetration ability under artificial insemination conditions.     

Comparison of the penetration ability of human spermatozoa into bovine cervical mucus and zona-free hamster eggs

In vitro bovine cervical mucus (BCM) penetration tests, sperm penetration assays (SPA) using zona-free hamster eggs, and routine semen analyses were performed on a total of 136 freshly collected semen samples from men who were seen at an infertility clinic. The correlations between bovine cervical mucus penetration and other semen parameters were the percent motile spermatozoa (r = 0.48), progressive motility grade (r = 0.44), sperm count (X 10(6)/ml) (r = 0.47), the percent normal morphology (r = 0.32) and the percent eggs penetrated (r = 0.46) (P less than 0.0001 for each correlation coefficient). When known fertile (n = 32) and infertile (n = 18) groups were tested, positive mucus penetration was associated 75% correctly and positive egg penetration was associated 90% correctly to clinical status. The mucus test had no false-negative results and the SPA had no false-positive results in these groups. It appears, then, that the mucus test and sperm penetration assay, although contributing different elements of data to an infertility evaluation, are both useful adjuncts to a semen analysis.     

Reassessment of the accuracy of traditional sperm characteristics and adenosine triphosphate (ATP) in estimating the fertilizing potential of human semen in vivo

Receiver operating characteristic curves and accuracy parameters were computed for traditional sperm characteristics (concentration, motility, morphology) and the number of peroxidase negative cells, and the concentration of adenosine triphosphate (ATP) in semen from populations of fertile and infertile men, and men who achieved a pregnancy after varicocele treatment. The percentage and concentration per millilitre of spermatozoa with rapid linear progressive motility, and the ATP concentration, provided the best discrimination between fertile and treated fertile from infertile men. The misclassification rate was higher for sperm morphology, total progressive motility and viability, whereas sperm concentration and the total sperm count per ejaculate had the worst discriminating power. The number of peroxidase negative cells per 100 spermatozoa was highly specific in identifying men who achieved pregnancy after varicocele treatment. The lower limit of normality of sperm characteristics was remarkably different between fertile men and men achieving pregnancy after treatment or during infertility work-up.     

Effect of alcohol intake and cigarette smoking on sperm parameters and pregnancy

Much has been published about smoking and alcohol intake influencing male fertility, sperm parameters and reproductive outcome. However, there is no conclusive agreement about the effects of cigarette smoking and alcohol use on these outcomes and thus no generally accepted guidelines. The combined effect of cigarette smoking and alcohol intake, though, has not been rigorously investigated. Because alcohol consumption and smoking are often seen together, this study focuses on the effect of smoking and drinking habits separately and combined on semen parameters, such as volume, sperm count, motility and morphology, and on pregnancy outcome. These suggested toxic effects are studied in a group of subfertile, asthenozoospermic men (<10% motile spermatozoa), compared with a group of ‘proven fertile’, healthy men. The extreme asthenozoospermic group has especially been chosen because of the suspected effect, that is, oxidative stress, on sperm motility. In our study, we found that cigarette smoking and alcohol intake did not differ between the subfertile and fertile group. In conclusion, cigarette smoking and alcohol consumption do not appear to significantly affect sperm parameters, such as volume, sperm count, motility and morphology or pregnancy outcome in our study population.     

上海地区正常生育力男性精液参考值初探

目的:回顾分析上海地区志愿捐精者与正常生育力男性精液分析各项主要参数的分布特征,比较两组男性精液质量的差别,探讨上海地区男性精液参数的正常参考值下限。方法:2010年10月至2011年7月上海市人类精子库招募正常生育力男性41例,健康捐精者100例,按《世界卫生组织人类精液检查与处理实验室手册》(第5版)进行精液常规检测,评估精液体积、精子浓度、前向运动(PR)精子百分率、精子总数和PR精子总数的均值,标准差,并进行t检验。同时统计正常生育力组上述各参数的分布,得出精液特征参数的正常参考值下限。结果:健康捐精组与正常生育力组精液常规各项主要参数(精液体积、精子浓度、PR精子百分率、精子总数、PR精子总数)间差异无统计学意义(P<0.05)。上海地区正常生育力男性精液参考值下限(P<0.05)为:浓度≥27.3×106/ml、PR≥8.1%、体积≥0.82 ml、精子总数≥44.73×106/1次射精、PR精子总数≥24.68×106/1次射精。结论:在评估男性生育力时,精子总数和PR精子总数可能是比精子浓度、精液体积和PR精子百分数更具参考价值的评价指标。     

A critical method of evaluating tests for male infertility

Considerable uncertainty surrounds the selection of test values that separate infertile from fertile men in the evaluation of male infertility. We herein describe an objective method of determining these values, referred to as threshold values, for different infertility tests. Using test results from fertile men threshold values were chosen such that 96 per cent of the semen samples from the fertile men were scored as fertile. These threshold values then were used to evaluate 100 semen samples from 74 men presenting for evaluation of infertility. Using this method we constructed infertility profiles on each of the 100 semen samples presented for infertility evaluation and found that the zona pellucida-free hamster egg penetration test (a measure of a spermatozoon's ability to undergo capacitation and penetrate an egg) identified 66 per cent of these samples as infertile, while multiple exposure photomicrography (a quantitative measure of sperm motility) identified 54 per cent of these samples as infertile. This compares with results from routine semen analyses using the same method, which identified none of the samples as infertile by sperm motility grade, 1 per cent by semen pH, 4 per cent by the percentage of motile sperm, 7 per cent by the total count of motile sperm, 10 per cent by the total sperm count, 11 per cent by the semen leukocyte concentration, 12 per cent by the concentration of motile sperm, 13 per cent by ejaculate volume, 16 per cent by sperm concentration and 27 per cent by sperm morphology. This method of analyzing infertility test results provides insight into the potential causes of male infertility and offers a critical approach towards understanding the complex problem of male fertility dysfunction.     

Effect of freeze–thawing procedure on chromatin stability, morphological alteration and membrane integrity of human spermatozoa in fertile and subfertile men

Cryopreservation is known to impair sperm motility and decrease the fertilization rate by detrimental effects on acrosomal structure and acrosin activity. However, the consequences of cryopreservation on the integrity of the sperm nucleus, chromatin stability and centrosome are less clear. The present study was designed to determine the effect of the freeze-thawing procedure on chromatin condensation (aniline blue staining) and the morphology (strict criteria) and membrane integrity of human spermatozoa. The structural and functional characteristics of the sperm plasma membrane were measured by the eosin-test and hypo-osmotic swelling test which were done separately. Sperm cryopreservation was performed on semen samples from two groups of men classified as fertile (n = 20) and subfertile (n = 72), based on their reproductive history and semen analysis according to WHO guidelines. The mean percentage of condensed chromatin, morphologically normal spermatozoa and membrane integrity in all semen samples investigated (n = 92) decreased significantly (p = 0.0001) after freeze-thawing, in comparison to the value observed prior to freezing. By comparing the semen samples between fertile and subfertile patients, significantly (p = 0.0009) greater damage was demonstrated in the subfertile than in the fertile group. Furthermore, no significant difference was observed between the two groups with regard to the morphological alteration and structural as well as functional damage of the sperm membrane. In conclusion, the freeze-thawing procedure significantly affects chromatin structure and sperm morphology, especially in the head and the tail regions, and this may explain the lower fertilization rate and IVF/ICSI outcome when frozen-thawed spermatozoa are used. In addition, this study demonstrates that chromatin condensation is a sensitive parameter for the evaluation of cryodamage of semen samples from fertile and subfertile patients, though subfertile patients with very poor semen characteristics have yet to be studied. It is therefore recommended that chromatin condensation be used as an additional parameter for the assessment of sperm quality after freeze-thawing.     

Evaluation of reference values of standard semen parameters in fertile Egyptian men

The reference values of human semen, published in the WHO's latest edition in 2010, were lower than those previously reported. The objective of this study was to evaluate reference values of standard semen parameters in fertile Egyptian men. This cross‐sectional study included 240 fertile men. Men were considered fertile when their wives had recent spontaneous pregnancies with time to pregnancy (TTP) ≤12 months. The mean age of fertile men was 33.8 ± 0.5 years (range 20–55 years). The 5th percentiles (95% confidence interval) of macroscopic semen parameters were 1.5 ml for volume and 7.2 for pH. The 5th percentiles of microscopic parameters were 15 million/ml for sperm concentration, 30 million per ejaculate for total sperm count, 50% for total motility, 40% for progressive motility, 62% for vitality, 4% for normal sperm forms and 0.1 million/ml for seminal leucocyte counts. In conclusion , fertile Egyptian men had higher reference values of sperm total motility, progressive motility and vitality, and lower reference values for total sperm counts as compared to those determined by the latest edition of the WHO laboratory manual in 2010. Other semen parameters were identical to those defined by the WHO 2010 manual.     

Effects of clinical stage and immunological status on semen analysis results in human immunodeficiency virus type 1-seropositive men

Summary. Complete semen analyses including computer-assisted sperm motility and morphology assessments were performed to determine if semen and sperm differed between HIV-seropositive men and fertile controls, or differed with symptoms, or CD4+ peripheral cell count categories. Previous studies included small numbers of men and presented conflicting conclusions. Two hundred and fifty non-vasectomized HIV-seropositive men and 38 fertile controls each provided one semen sample. Non-parametric statistics were used to analyse both continuous and nominal data. Fertile men had significantly greater semen volume, sperm concentration, percent motility, percent rapid and linear motility and total strictly normal spermatozoa than HIV seropositive men. Neither total number nor subtypes of leukocytes in semen differed between the two groups. Among the HIV seropositive men, significant differences in semen analyses were found between CD4+ cell count, clinical, and AIDS categories. Lower CD4+ cell counts (<200 mm⁻³) were associated with significantly lower percent motility, percent normal sperm morphology by strict criteria, significantly more spermatids in semen, and higher percentages of teratozoospermia, oligoasthenoteratozoospermia and leukocytospermia. Healthier men, based on clinical categories, had significantly more normal shaped spermatozoa and fewer had azoospermia, oligoasthenoteratozoospermia or leukocytospermia. Many HIV-seropositive men have normal semen analyses, but as the disease progresses more defects are found, particularly in strict criteria sperm morphology.     

Relationship of spermatozoal DNA fragmentation with semen quality in varicocele‐positive men

The aim of the study was to assess the semen quality and levels of spermatozoal nuclear DNA fragmentation in subfertile subjects clinically diagnosed with varicocele, subfertile subjects without varicocele and healthy fertile controls. Semen samples were obtained from 302 subjects. Of them, 115 were healthy fertile controls having normal semen characteristics, 121 subfertile men diagnosed with varicocele, both, clinically and on ultrasonography, while 66 subjects were subfertile with no varicocele. Spermatozoal concentration, percentage motility, morphology and DNA fragmentation were measured. In the study population, deterioration in semen quality‐decreased spermatozoal concentration, percentage motility and normal morphology was seen in subfertile subjects, especially with varicocele. Highest spermatozoal DNA fragmentation was observed in varicocele‐positive subjects as compared with varicocele‐negative subjects and healthy fertile controls. Significant negative correlation was seen between spermatozoal DNA fragmentation and concentration (r = ?0.310), motility (r = ?0.328) normal morphology, WHO method (r = ?0.221) and Tygerberg strict criteria (r = ?0.180) in the varicocele‐positive subfertile subjects. In conclusion, this study suggests existence of a negative relationship between spermatozoal DNA fragmentation and semen quality in varicocele‐positive subfertile subjects.     

Pyriform head: a frequent but little-studied morphological abnormality of sperm

This study was conducted to investigate the frequency of sperm with a pyriform head in semen samples, to determine the percentage of the occurrence of this abnormal sperm form, and to assess its possible correlation with other semen parameters. The study was designed as a retrospective data analysis in the setting of an andrology laboratory at a tertiary-care academic hospital. Semen quality data were analyzed from 114 subfertile men and 60 fertile men. The Student's t test, the Mann-Whitney nonparametric test, and the Pearson correlation coefficient were used for statistical analysis. Sperm with a pyriform head were present in the semen samples of 98% of the subfertile men and 100% of the fertile men; the percentage of this abnormal sperm form was 22 +/- 14.9% in subfertile and 13% +/- 7.8 in fertile men (p <.001); 16% of the subfertile men presented a higher percentage of these abnormal sperm than the normal upper limit. In some subfertile men with a high percentage of sperm with a pyriform head, their subfertility could be attributed to the cause that produces this morphological abnormality. Moreover, morphological abnormalities in the neck and the tail, as also a cytoplasmic droplet, are significantly more frequent in sperm with a pyriform head than in sperm with a normal head.     

Effect of Sp-cAMP on sperm motility in patients with unexplained infertility

Summary. Sperm motility is one of the most important semen parameters affecting the fertility of an individual. Sp-cAMP, a thiophosphate analogue of c-AMP, is a phosphodiesterase inhibitor controlling the intracellular c-AMP levels which in turn influences sperm motility. The results in our laboratory on a group of suspected subfertile men and fertile donors showed significant enhancement of sperm motility after incubation of washed sperm with various doses of Sp-cAMP.     

Relationships between serum hormone levels and semen quality among men from an infertility clinic

Participation rates in epidemiologic studies on semen quality are generally very low, raising concerns as to the potential for selection bias. Since hormones both initiate and maintain spermatogenesis, they may serve as surrogates of semen quality in epidemiologic studies. For this reason, in the present study, we explored the influence and predictive ability of reproductive and thyroid hormones on semen quality among men who were partners in an infertile couple. Between 1999 and 2003, 388 men were recruited from Massachusetts General Hospital Andrology Laboratory for clinical evaluation of fertility status. Fresh semen samples were assessed for quality (concentration, motility and morphology) and the serum levels of hormones, including follicle-stimulating hormone (FSH), luteinizing hormone (LH), inhibin B, sex hormone-binding globulin (SHBG), testosterone, free androgen index, free T4, total T3, and thyroid-stimulating hormone (TSH), were measured. Multiple logistic regression revealed increased odds for below-reference sperm concentration and morphology in men with increased FSH, and decreased odds for below-reference sperm concentration and motility in men with increased inhibin B. When FSH and inhibin B were divided into quintiles, the relationships with sperm concentration showed evidence of a threshold value. However, the ability of specific FSH (10 IU/L) and/or inhibin B (80 pg/mL) cutoff values to predict semen quality was lower than in previous reports. In multiple linear regression analysis, FSH and LH were inversely associated with sperm concentration, motility, and morphology. Inhibin B and free T4 were positively associated with sperm concentration, while there was a suggestive positive association between testosterone and sperm motility. In conclusion, we have found that FSH, LH, inhibin B, testosterone and free T4 levels are associated with human semen parameters. Additional consideration should be given to the utility of serum hormone levels as a surrogate for semen quality in epidemiologic studies in which the collection of semen is difficult due to logistical and/or volunteer rate constraints.     

Reduced penetration of zona-free hamster ova by cryopreserved human spermatozoa

The effect of cryopreservation on human sperm fertilizing potential was assessed by using the human sperm penetration into zona-free hamster ovum test. Semen samples from 12 fertile men were compared before and after cryopreservation for motility, sperm penetration rate, and number of sperm cells incorporated per oocyte. In fresh samples sperm concentration was 102 +/- 51 X 10(6) cells/ml, motility 66 +/- 14%, penetration rate 77.8 +/- 19%, and sperm incorporation 4.3 +/- 3.9 sperm per ovum. Frozen-thawed sperm cells showed a marked reduction of 61 +/- 21% (p less than 0.001) in motility. Penetration rate was reduced by 53 +/- 34% (p less than 0.01), and sperm incorporation dropped by 50 +/- 28% (p less than 0.05). Despite this substantial reduction in all three parameters, 75% of the samples maintained a penetration rate exceeding 14%, which is the lower limit for fertile semen. For the individual subject the decrease in sperm motility did not reflect actual fertility potential as expressed by its ability to penetrate zona-free hamster ova. These findings are related to morphological and biochemical changes in frozen-thawed semen and apparently are correlated with the decrease in pregnancy rates after cryopreservation. This test may be a valuable supplement to routine microscopic semen analysis for semen cryopreservation candidates.     

Sperm chromatin heterogeneity as an infertility factor

Semen samples from husbands with a history of unexplained infertility (n = 33), of women with habitual abortion (n = 36), or normal fertile donors (n = 20) were subjected to conventional semen analysis (SA), Acridine orange test (AOT), and zona-free hamster egg penetration test (HEPT). The three tests operate independently. The most discriminatory test was AOT (p = 0.0001) followed by HEPT (p = 0.019). The frequency of sperm chromatin heterogeneity as detected by AOT red fluorescence was highest in habitual abortion (39.4%), followed by unexplained infertility (16.4%), and, last, donors (9.4%). However the percentage of penetration was highest in habitual abortion (50.7%), followed by donors (43.1%), and least in unexplained infertility (33.9%). Conventional semen parameters (sperm density, motility, abnormality, and vitality) were the least to discriminate between the three groups. The presence of abnormal sperm chromatin may lead to infertility as a result of early pregnancy loss.     

Nonsperm cells in human semen and their relationship with semen parameters

The prevalence and clinical significance of leukocytes (WBC) and immature germ cells in semen is currently a matter of controversy. The aim of this work was to assess the prevalence of leukocytospermia in semen samples from Venezuelan men and its possible effects on sperm parameters. The concentration of WBC and round cells (RC) was evaluated in 118 semen samples from 19 fertile subjects (group 1), 62 infertile patients (group II), and 37 men with varicocele (group III). Semen WBC concentration was assessed by peroxidase assay. Twenty-six (22%) of the total samples had more than 10 WBC/mL semen. Twenty of the infertile men had leukocytospermia (32%) compared with 16% in the fertile group and 8% in the varicocele group. Semen RC concentration was lower than 5 x 10(6)/mL in all groups but, in groups II and III was significantly higher compared with group I. Infertile men had the highest WBC concentration. WBC concentration was negatively correlated with progressive motility, percentage of morphologically normal sperm, and hypoosmotic swelling test in infertile men but not in the varicocele group. In this group a negative correlation was obtained between immature germ cells and normal sperm morphology. The data show that leukcytospermia occurs frequently in infertile patients and is associated with poor semen quality parameters. In contrast, in men with varicocele, the increased number of immature germ cells might play a pivotal role in the pathogenesis of abnormal spermatozoa.     

Are conventional sperm morphology and motility assessments of predictive value in subfertile men?

Sperm morphology and motility are believed to be important prognostic factors for fertility. Results of a group of 67 men investigated for primary infertility who had mean sperm concentrations greater than 5 million per ml and who later produced pregnancies, were compared with those of 67 matched controls who remained infertile. All female partners were potentially fertile. The groups were matched for other known prognostic factors for fertility, namely, wife's age, the duration of infertility, sperm concentration and varicocele size. There were no significant differences between the two groups overall in the (mean +/- SEM)% of sperm with normal morphology (58.3 +/- 2.1; 58.5 +/- 2.2), or motility (40.6 +/- 1.8; 37.0 +/- 2.0). However, among oligospermic men from the two groups, sperm motility was significantly higher (P less than 0.05) in the subsequently fertile group (43.1 +/- 2.6%) than in the persistently infertile group (33.3 +/- 3.7). These results indicate that sperm morphology as currently assessed may not be important in predicting fertility in subfertile men with a mean sperm concentration over 5 million/ml and the % sperm motility may only be a relevant predictor in oligospermic men.