Seasonal variations and age-related changes in human sperm count, motility, motion parameters, morphology, and white blood cell concentration

Relationship of environmental exposure temperature and temperature extremes on sperm DNA fragmentation index in men with different BMI values and the indirect effect of DNA fragmentation index on semen parameters

Prior studies have established a significant correlation between the DNA fragmentation index (DFI) and infertility. Additionally, certain investigations suggest that environmental exposure may serve as an etiological factor impacting semen quality. This study aimed to explore the impact of season, ambient temperature, and weather extremes on the DFI of sperm, along with other relevant parameters. Furthermore, it sought to assess how ambient temperature affects the DFI of sperm and other semen parameters in populations with varying BMI values. Additionally, the study analyzed the transient indirect effect of DFI on sperm parameters. This retrospective study analyzed semen samples from 11,877 men, selected based on female factor considerations, spanning from January 2016 to December 2021. Participants were grouped according to the season of semen collection. The results showed that samples collected in summer had a lower semen volume and sperm motility, while those collected in autumn had a lower DFI. We analyzed the exposure-response ratio between environmental exposure temperature and semen parameters using a generalized additive model. Results showed that the curve of the exposure-response relationship was U-shaped or inverted U-shaped; when the air temperature exposure was below the threshold, for each degree of temperature increase, the total sperm motility, sperm concentration, and progressive motility increased by 0.16 %, 0.29 × 10 (Levine, 1999)/ml and 0.14 %, respectively, while the DFI and inactivity rate decreased by 0.078 % and 0.15 %, respectively. When the air temperature exposure exceeded the threshold, for each degree of temperature increase, the sperm concentration, total sperm motility, semen volume and progressive motility decreased by 0.42 × 10 (Levine, 1999)/ml, 0.11 %, 0.0078 ml and 0.15 %, respectively, while the DFI and inactivity rate increased by 0.13 % and 0.12 %, respectively. Extremely cold weather during spermatogenesis was positively correlated with DFI, and extremely hot weather was negatively correlated with sperm motility. Subgroup analysis revealed that individuals classified as overweight / obese exhibited more pronounced changes in sperm parameters and the DFI in response to variations in environmental exposure temperature compared to those with a normal BMI. In the analysis of the relationship between DFI and sperm parameters, the results showed an inverted U-shape relationship between DFI and semen volume, and a negative correlation between DFI and sperm concentration and sperm motility. And we found that ambient temperature affects sperm parameters through DFI at low as well as average temperatures, whereas at high temperatures this indirect effect is no longer present.

Is there an association between family members' season of birth that could influence birth seasonality? Evidence from Spain and France

The number of births varies by season. Research on birth seasonality has shown that women's season of birth somehow influences that of their children, but factors underlying the intergenerational transmission of birth seasonality remain unknown. With data from Spain and France, we analysed the possibility of transmission of birth season between generations, testing whether relatives tended to be born in the same season. Results indicated that there was an association-a similarity-between parents' and children's birth seasons, partially explaining the stability of seasonal patterns over time. This association also existed between parents' birth seasons. While parents' association is directly explained by an excess of marriages with spouses born in the same month, the overall association may be explained by two facts: different socio-demographic groups show differentiated birth patterns, and relatives share socio-demographic features. Birth season seems to be related to family characteristics, which should be controlled for when assessing birth-month effects on subsequent social/health outcomes.

Impact of Seasonal Variations on Semen Parameters: A Retrospective Analysis of Data from Subjects Attending a Tertiary Care Fertility Centre

Background

Seasonal variations in semen parameters have been detected in many previous studies, mostly conducted in the West and Mediterranean countries. Located in a tropical region, we have only three seasons - summer, winter and rainy season. Literature search did not reveal studies from Indian subcontinent.

Aims

Our objective was to find if our climate produced seasonal variations in semen parameters such as sperm concentration (SC), total motile SC, morphology and vitality, which may have implications in fertility management.

Settings and Design

This is a descriptive study, conducted at a tertiary level hospital. Semen analysis reports of male partners of all infertile couples during the 4-year period from 2019 to 2022 were analysed.

Materials Methods

The data were collected from records of all infertile couples registered for the treatment in the department during the study period. Semen analysis reports of male partners of all infertile couples attending outpatient department of the Reproductive Medicine Department during the 4-year period from January 2019 to December 2022 were collected. The data of azoospermic and severe oligospermic (<5 million/mL) men and those receiving hormone treatment were excluded.

Statistical Analysis Used

Data were analysed using SPSS 23 and variables expressed as mean and standard deviation. Changes in mean values over years and over seasons were evaluated using F-test. Post hoc analysis was done using Sidak method. P < 5% was considered statistically significant.

Results

The data of 2326 patients were analysed. SC was lowest during summer but was not statistically significant. Sluggishly motile sperm per cent was maximum in rainy season (P = 0.002). Post hoc analysis showed significant variations in summer samples compared to both rainy and winter seasons. Head defect (HD) and tail defects showed a significant seasonal variation (P = 0.011 and P = 0.024, respectively), lowest HD seen in rainy season.

Conclusion

Semen parameters showed seasonal variations, with favourable features in colder climates, and may need to be considered in infertility management, especially if the male is oligospermic.

Influence of climatic conditions in the mesothermal climate area on pregnancies following elective fresh single blastocyst transfer

PURPOSE

To investigate the effect of climatic parameters in the mesothermal climate area on clinical pregnancy and live birth following fresh single blastocyst transfer.

METHODS

This study investigated clinical pregnancies and live births that resulted from 555 ovarian stimulation cycles followed by fresh single blastocyst transfer. The samples were stratified according to climatic conditions (low T, temperature < 12.9 °C; middle T, 12.9 °C ≤ temperature < 22.6 °C; high T, temperature ≥ 22.6 °C; low H, relative humidity < 62.1%; middle H, 62.1% ≤ relative humidity < 66.5%; high H, relative humidity ≥ 66.5%; short S, sunlight duration < 5.2 h; middle S, 5.2 h ≤ sunlight duration < 6.7 h; long S, sunlight duration ≥ 6.7 h). Clinical pregnancy and live birth rates among three groups from each climatic parameter were compared. Multivariable analyses were performed to investigate the effects of climatic conditions on blastocyst development, endometrial thickness, clinical pregnancy, and live birth.

RESULTS

A statistically significant difference was found in pregnancy rates among low T (48.8%), middle T (37.3%), and high T (36.6%) groups. Multivariable analyses revealed that temperature was associated with clinical pregnancy and live birth rates with adjustment for patient age, BMI, type of ovarian stimulation, endometrial thickness, and expansion grade of the transferred blastocyst. The association between climatic parameters and blastocyst development and endometrial thickness was not confirmed.

CONCLUSIONS

This study suggests that lower temperatures in the mesothermal climate area could favorably affect the rates of clinical pregnancy and live birth achieved by fresh single blastocyst transfer.

Influence of sociodemographic factors in birth seasonality in Spain

OBJECTIVES

The goal of the present research is to establish for the first time a hierarchy of sociodemographic factors according to their importance influencing birth seasonality.

METHODS

We used Vital Statistics data on all births registered in Spain in the period 2016-2019. Differences in the degree of seasonality between sociodemographic groups (defined by maternal age, maternal marital status, maternal education, birth order, maternal job qualification, maternal employment status, maternal location population size, and maternal country of birth) were first examined with descriptive techniques. Secondly, analysis through alternative Data Mining techniques determined the association between sociodemographic factors and birth seasonality and the factors importance rank.

RESULTS

Those factors related to maternal labor status (employment status, job qualification, and education) were found to be the most relevant influencing birth seasonality. It was found that the overall seasonal pattern in Spain was driven by lower skilled employed mothers, in contrast with not employed or high skilled employed mothers, who showed a different or weaker seasonality. Finally, we found that a change in the rhythm pattern has taken place in the last decades in Spain.

CONCLUSIONS

Birth seasonality is to a large extent related to maternal employment status. Employed mothers, normally more affected by the seasonality of work calendar than the unemployed, show higher conception rates structured around holidays. This may indicate that the observed change of seasonal pattern in Spain in the last decades, as in other European countries, may be specifically driven by the progressive higher participation of women in labor market.

Temporal patterns of weekly births and conceptions predicted by meteorology, seasonal variation, and lunar phases

BACKGROUND

Data reporting the number of births given by women resident in Vienna for each week between 1999 and 2019, and the duration (in weeks) of their pregnancies, were used to estimate the week of conception. When preliminary examinations detected cyclical patterns for births and conceptions, a series of Poisson regressions for births and conceptions were performed to assess whether these cycles could be associated with lunar or solar phases.

METHODS

To that end 2 sine-cosine functions, 1 with a wavelength of 1 year (365.25 days) and 1 with a wavelength of 29.529 days, the latter resembling the average length of a lunar cycle, were constructed. In addition, also average weekly temperatures were included in the models.

RESULTS

Same week temperature was a strong non-linear predictor for both births and conceptions. Extreme temperatures, especially hot temperatures, increased the number of births while the numbers of successful conceptions were decreased by extreme temperatures. Regarding annual variation in conceptions, the lowest values were found in May and the highest in late autumn and early winter. Therefore, the highest numbers of births are observed in the summer. As per lunar variations, the highest numbers of conceptions occurred at the full moon and the highest numbers of births at the waxing crescent to first quarter moon.

DISCUSSION

The latter results should be treated with caution, as they are not hypothesis driven. Furthermore, literature reports on this topic are conflicting. Nevertheless, these findings will be useful in further analyses examining air pollution effects.

Seasonal variation in semen quality is not associated with fecundity in the Utah Population Database

We determine whether a suspected seasonal variability in semen quality affect subsequent live birth rates. This is a retrospective, cohort analysis of men who provided semen analyses as part of fertility workup through a large andrology lab between 1996 and 2013 and corresponding birth rates using the Utah Population Database (UPDB). Semen parameters were analysed including total motile count (TMC), total sperm count, sperm concentration and progressive motility. Corresponding live births reflect those born in the state of Utah and were derived from birth certificate data available in the UPDB. Descriptive statistics were reported along with linear regression analysis with mixed effected models to test for an interaction between seasonal variation in semen quality and birth rates, accounting for age at the time of the semen analysis and abstinence time. A total of 11,929 patients and 14,765 semen samples were included. Only 3597 men (39% of men) had one or more values outside the World Health Organization reference range for their semen parameters. Linear regression demonstrated a consistent U-shaped relationship between TMC, total sperm count, and sperm concentration and season, with spring and winter yielding the highest values with a decline in the summer and fall. 7319 of these males had recorded live births for a total of 13,502 live births during the study period after a median follow-up of 7.2 years (IQR: 3.9-11.0). We did not find a significant interaction between specific semen parameters for a specific season and subsequent live births. Semen quality was the highest in the spring and winter, however there was no interaction between seasonal variability in semen quality and subsequent births. This is one of the largest studies describing seasonal variation in semen quality in humans.

Parasitic Load, Hematological Parameters, and Trace Elements Accumulation in the Lesser Spotted Dogfish Scyliorhinus canicula from the Central Tyrrhenian Sea

Parasitological, hematological, and ecotoxicological analyses were carried out on a population of lesser spotted dogfish Scyliorhinus canicula from the central Mediterranean Sea. Parasitological analyses highlighted a poor helminthic community, highly dominated by a single taxon represented by the cestode Nybelinia sp. No differences in the parasitic load between females and males were observed. Hematological analyses showed that the number of leukocytes was significantly lower in the sharks that resulted in parasitism, and this could be due to the ability of some trace elements, such as arsenic, weakening the immune system and exposing animals to a higher risk of parasite infection, although further hematological and parasitological analyses are required on a larger number of samples. Trace elements analyses in the vertebrae, skin, and liver highlighted that the most abundant and potentially toxic elements were lead (Pb), arsenic (As), and cadmium (Cd). Other trace elements were also abundant, such as manganese (Mn), zinc (Zn), nickel (Ni), copper (Cu), and iron (Fe). Pb, As, and Mn showed the highest concentrations in vertebrae, while Cd, Cu, and Zn were the highest in the liver, probably due to their concentration in the prey items of the sharks; Fe and Ni showed the highest concentrations in the skin, due to their presence in the water column, especially along the coast where animals were collected. The concentration of some trace elements analyzed in the vertebrae decreased with the growth of the sharks. These results confirm that elasmobranchs, being predators at the apex of the marine food chain, act as final receptors for a series of polluting elements regularly discharged into the sea.

Analysis of the screening results of 24040 potential sperm donors in a human sperm bank in Henan Province, China: a 14-year retrospective cohort study

STUDY QUESTION

Is there a relation between the characteristics of potential sperm donors and the acceptance rate of these potential donors?

SUMMARY ANSWER

A relatively higher acceptance rate was observed for potential sperm donors who were aged ≤ 35 years, were married, had children, and who had received higher education, and acceptance rates were also higher during spring and winter than summer and autumn.

WHAT IS KNOWN ALREADY

Recruiting donors to a sperm bank program is difficult and slow owing to the high rates of rejection and dropout.

STUDY DESIGN, SIZE, DURATION

A total of 24040 potential sperm donors were screened by the Henan Human Sperm Bank from 2006 to 2019.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Potential sperm donors were recruited using the following baseline requirement: height of 168 cm or taller; age 22-45 years; currently attending or had graduated from high school or above. Men who met the criteria for age, height, and education level were invited for semen quality screening. The acceptable criteria for semen samples included liquefaction time < 60min, volume ≥ 2mL, sperm concentration ≥ 60 × 106/mL, progressive motility ≥ 60%, post-thaw motility ≥ 40%, pre-freezing total motile sperm per vial > 30 × 106/mL, post-thaw total motile sperm per vial > 12 × 106/mL, and freeze-thaw survival rate ≥ 60%. Any potential sperm donors meeting the minimum criteria for acceptable semen quality on two consecutive semen samples were scheduled for clinical assessment, physical examination, and laboratory tests. The reasons for sperm donor rejection were analyzed. The characteristics of accepted and rejected donors were compared using the chi-square test, and multivariate logistic regression analyses were conducted to identify factors associated with the acceptance rate of potential sperm donors and the positive rate of sexually transmitted diseases (STDs).

MAIN RESULTS AND THE ROLE OF CHANCE

Only 23.38% (5620/24040) of potential sperm donors were accepted. The top four reasons for rejection were suboptimal semen quality (90.27%), STDs (6.26%), dropped out (2.65%), and chromosomal abnormalities (0.35%). The most common reason for the rejection of donors with an STD was a positive test for mycoplasmas (49.05%), followed by hepatitis B virus (27.56%), Chlamydia trachomatis (4.68%), and Escherichia coli (3.03%). n this study, the acceptance rate for men aged ≤ 35 years was significantly higher than that for men aged >35 years (P < 0.05). The acceptance rates were also significantly higher for men with a higher education than for men with lower education, married men than unmarried men, and men with children than men without children (P < 0.05). Moreover, acceptance rates were significantly higher during spring and winter than during summer (P <0.05) but were not significantly higher during autumn than during summer (P >0.05).

LIMITATIONS, REASONS FOR CAUTION

This study was not performed to analyze the effect of lifestyle habits, such as alcohol consumption and cigarette smoking, on the acceptance rate of potential sperm donors.

WIDER IMPLICATIONS OF THE FINDINGS

Only a small proportion of potential sperm donors were accepted in this anonymous sperm donor program. New strategies for sperm donor recruitment may be required to improve the acceptance rate. In the future, we may have to target potential sperm donors who are aged ≤ 35 years and who received higher education in order to improve the acceptance rate.

STUDY FUNDING/COMPETING INTEREST(S)

This work was supported by the Joint Construction Project of Henan Medical Science and Technology Research Plan under grant number LHGJ20190389. The authors report no conflict of interest.

TRIAL REGISTRATION NUMBER

N/A.

Application of Selenium Nanoparticles on Sperm Quantity Indicators in Wistar Rat

Background: Antioxidant enzymes and selenium in semen plasma have vital effects on reducing lipid peroxidation of spermatozoid membrane in elderly organisms by preventing the destructive effects of reactive oxygen species. Therefore, the use of antioxidants and selenium is essential for normal testicular function and spermatogenesis. Methods: In this experimental study, 44 male Wistar rats aged 2.5 months (young) and 44 male Winstar rats aged 11 months (old) were separated into 4 groups of control, placebo, experimental 1 (0.2 mg/kg BW), and experimental 2 (0.4 mg/kg BW). Rats encountered weekly surgery after a week of receiving different treatments. Resection of their testes was used for histological studies. Results: The number of spermatocytes, spermatid, and spermatozoa in young and old rats increased during the study period. In young rats, the highest number of these cells remarked in the third and fourth weeks of the experiment using selenium nanoparticles (ranged from 165.3 to 285.3 × 106). For old rates, the highest number of the abovementioned cells observed in the second week of the experiment (ranged from 143.3 to 146.7 × 106). Variables of treatment, week, and age presented significant effects on the number of testicular germ cells. Also, applied treatments had no significant effect on the sperm quality characteristics of rats. The number of Sertoli and Leydig cells did not show a significant difference compared to the control group. The results showed a positive and highly significant correlation between spermatozoid, spermatocytes, and spermatocytes. The findings also indicated the same genetic and environmental effects on the traits. Therefore, any spermatocyte shift will have a direct influence on the spermatozoid. Conclusions: This study demonstrated that using selenium nanoparticles in young and old age groups in rats could improve testicular germ cells, especially in the old group. Therefore, with growing age and decreasing sperm quality, selenium nanoparticles can be used due to their positive effect on sperm parameters and their low health risk.

Age-related changes in human conventional semen parameters and sperm chromatin structure assay-defined sperm DNA/chromatin integrity

RESEARCH QUESTION

What are the correlations between male age, traditional semen parameters, sperm DNA fragmentation index (DFI) and high DNA stainability (HDS) in a sufficiently large sample size?

DESIGN

Retrospective cohort study of 18,441 semen samples, with data divided into seven age groups according to male age: ≤25, 26-30, 31-35, 36-40, 41-45, 46-50 and ≥51 years.

RESULTS

Age was negatively correlated with semen volume, total sperm count, motility and HDS, and positively correlated with sperm concentration and DFI (P < 0.001). After 35 years of age, semen volume and total sperm count began to decline. After 30 years of age, motility and HDS decreased consistently. Sperm concentration and DFI increased from 26-30 years of age. DFI was negatively correlated with sperm concentration, total sperm count, motility and normal morphology (P < 0.001) and positively correlated with semen volume and HDS (P < 0.001). HDS was negatively correlated with all parameters (P < 0.001) except semen volume (r = -0.013, P = 0.074) and DFI (r = 0.124, P < 0.001). Patients aged ≥40 years had higher DFI than those aged <40 years in the entire cohort, in the abnormal semen parameters cohort, and in the normal semen parameters cohort (OR 2.145, 2.042, 1.948, respectively, P < 0.001). The ≥40 years age group had a lower HDS than the <40 years age group in the entire cohort and abnormal semen parameters cohort (OR 0.719, 0.677, respectively, P < 0.001).

CONCLUSIONS

Ageing is a negative effector of sperm quantity and quality, and routine sperm parameters have weak but significant correlations with sperm DNA/chromatin integrity.

The effect of seasonality on reproductive outcome of patients undergoing intracytoplasmic sperm injection: A descriptive cross-sectional study

Background

There is conflicting evidence regarding the impact of season on the assisted reproductive technology outcome.

Objective

To retrospectively compare three year outcome of women undergoing their first intracytoplasmic sperm injection cycle, across seasons.

Materials and Methods

In this descriptive cross-sectional study, 3,670 women who underwent their first intracytoplasmic sperm injection cycle in Mehr Medical Institute, Rasht, Iran between April 2010 and May 2014 were studied. Women were divided into four groups according to the day of oocyte retrival as: spring (n = 808), summer (n = 994), autumn (n = 1066), and winter (n = 802). Basal and stimulation charecteristics were compared among groups.

Results

While sperm concentration and motility were significantly lower during summer, the total number of retrieved and metaphase II oocytes were significantly higher (p = 0.0001, p = 0.0001, p = 0.004, p = 0.02, respectively). Fertilization rate were significantly higher during autumn (p = 0.0001). Also, the number of high- quality transferred embryos were significantly higher during summer and winter (p = 0.03). A similar pattern was observed in implantation rate and pregnancy over the four seasons.

Conclusion

Despite the fact that intracytoplasmic sperm injection minimize the seasonal effect on pregnancy outcome, changes in pregnancy rate still occur among different seasons without particular pattern. It seems that performing assisted reproductive technology procedures in a particular season should be considered as an effective factor.

Oxidative Stress and Reproductive Function in the Aging Male

With the delay of parenthood becoming more common, the age at which men father children is on the rise. While the effects of advanced maternal age have been well documented, only recently have studies started to focus on the impact of advanced paternal age (APA) in the context of male reproduction. As men age, the antioxidant defense system gradually becomes less efficient and elevated levels of reactive oxygen species (ROS) accumulate in spermatozoa; this can impair their functional and structural integrity. In this review, we present an overview of how oxidative stress is implicated in male reproductive aging by providing a summary of the sources and roles of ROS, the theories of aging, and the current animal and human studies that demonstrate the impacts of APA on the male germ line, the health of progeny and fertility, and how treatment with antioxidants may reverse these effects.

Semen quality pattern and age threshold: a retrospective cross-sectional study of 71,623 infertile men in China, between 2011 and 2017

BACKGROUND

The aim of this study was to provide information on the semen quality pattern of infertile men and age thresholds for semen parameters in China.

METHODS

This was a retrospective cross-sectional study investigating 71,623 infertile men from the Reproductive and Genetic Hospital of CITIC Xiangya in Hunan, China, from 2011 to 2017. The Kruskal-Wallis test, Mann-Kendall test, linear regression model and joinpoint regression were used.

RESULTS

Although erratic changes were observed in the median semen parameters (sperm concentration 40.1-52.1 × 10⁶/ml, total sperm count 117.8-153.1 × 10⁶, sperm progressive motility 33.4-38.1%) during the 7 years of observation, no significant decrease in semen quality was found, and 47.88% of infertile men showed normal semen parameters according to the World Health Organization (WHO) criteria. According to the joinpoint regression analysis, sperm progressive motility appeared to decrease earlier than the sperm concentration and total sperm count (at 28, 58, and 42 years of age, respectively).

CONCLUSIONS

There is no evidence of a deterioration in semen quality among infertile men in Hunan, China. Semen parameters decreased with increasing age, with turning points noted at different ages. Semen parameters are not absolute evidence for the assessment of male fertility potential. Therefore, we believe that, among semen parameters, the sperm concentration is the best predictor of fertility for ART, followed by motility. Decreased sperm motility may affect natural pregnancy, but it is not necessary for successful IVF.

Sperm physiology varies according to ultradian and infradian rhythms

The spermatozoon must be physiologically prepared to fertilize the egg, process called capacitation. Human sperm samples are heterogeneous in their ability to capacitate themselves, which leads to variability between samples from the same or different donors, and even along the seasons. Here we studied sperm variation in the capacitation state according to the ability of capacitated spermatozoa to acrosome react upon stimulation (% ARi) and to be recruited by chemotaxis (% Chex). Both indirect indicators of sperm capacitation increased along the incubation time with fluctuations. Those capacitated sperm recruited by chemotaxis showed an ultradian rhythm with a cycle every 2 h, which might be influenced by unknown intrinsic sperm factors. Two infradian rhythms of 12 months for the % ARi and of 6 months for % Chex were observed, which are associated with the joint action of temperature and photoperiod. Thus, to avoid false negative results, human sperm samples are recommended to be incubated for a long period (e.g. 18 h) preferably in spring time. This innovative point of view would lead to better comprehend human reproductive biology and to think experimental designs in the light of sperm cyclicity or to improve sperm aptitude for clinical purposes.

Relationship between seasons and pregnancy rates during intrauterine insemination. A historical cohort

BACKGROUND

The underlying cause of seasonal infertility in humans is unclear, but is likely to be -multifactorial.

OBJECTIVE

The aim of our study was to compare the pregnancy rates among infertile women who underwent induced ovulation and intrauterine insemination (IUI) with the season in which the fertility treatment was performed.

DESIGN AND SETTING

This retrospective cohort study was conducted on 466 patients who were treated in the reproductive endocrinology and infertility outpatient clinic of a tertiary-level women's healthcare and maternity hospital.

METHODS

Retrospective demographic, hormonal and ultrasonographic data were obtained from the patients' medical records. Clomiphene citrate or gonadotropin medications were used for induced ovulation. The patients were divided into four groups according to the season (spring, winter, autumn and summer) in which fertility treatment was received. Clinical pregnancy rates were calculated and compared between these four groups.

RESULTS

There were no significant differences between the seasonal groups in terms of age, infertility type, ovarian reserve tests, duration of infertility, medications used or length of stimulation. A total of 337 patients (72.3%) were treated with clomiphene citrate and 129 (27.7%) with gonadotropin; no significant difference between these two groups was observed. The clinical pregnancy rates for the spring, winter, autumn and summer groups were 15.6% (n = 24), 8.6% (n = 9), 11.5% (n = 13) and 7.4% (n = 7), respectively (P = 0.174).

CONCLUSIONS

Although the spring group had the highest pregnancy rate, the rates of successful IUI did not differ significantly between the seasonal groups.

A model investigating environmental factors that play a role in female fecundity or birth rate

OBJECTIVE

Over 12% of women in the United States have reduced fertility and/or fecundity. Environmental factors, such as temperature, and socioeconomic factors have been implicated in reducing female fecundity. The purpose of this study is to investigate the effect of environmental factors coupled with socioeconomic factors on birth rate at the country-level. We use birth rate as a proxy for female fecundity. This will enable us to identify the most important factors affecting female fecundity.

METHODS

Using country-specific data from 182 countries, we constructed a regression model of the effects of environmental and socioeconomic factors on birth rate at the country-level. Our model assesses the role of temperature, Gross Domestic Product (GDP) per capita, fine air particulate matter (PM 2.5), and prevalence of male and female Body Mass Index (BMI) > = 25 (age-standardized) on birth rate per country. Because many of these factors are inter-dependent, we include all possible two-way interaction terms to assess the role of individual factors and interactions between multiple factors in the model.

RESULTS

In the full regression model, we found that GDP per capita along with 5 interaction terms were significant after adjusting for multiple testing. Female BMI was only nominally significant. GDP per capita was independently associated with birth rate (adjusted p-value <0.001). Prevalence of BMI > = 25 age-standardized in males and females were also significant when interacting with air pollution or GDP on female fecundity (birth rate). Temperature did not affect birth rate either independently or as an interaction unless BMI was removed from the model.

CONCLUSION

A country's economic wealth was the most significant factor in predicting birth rate in a statistical model that includes environmental and socioeconomic variables. This is important for future studies investigating environmental factors involved in increasing or decreasing female fecundity.

Gradient sperm selection for reproductive techniques in cattle: Is Isolate a suitable replacement for Percoll?

In assisted reproductive techniques, it is essential to perform a sperm selection to obtain spermatozoa with high motility and membrane integrity for in vitro fertilisation (IVF) and high-DNA integrity for intracytoplasmic sperm injection (ICSI). In this study, we evaluated whether Isolate^® was a suitable substitute for Percoll^® for assisted reproductive techniques. Commercial cryopreserved bovine semen was used after selection in both gradients, and plasma and acrosome membrane integrity, reactive oxygen species (ROS) levels, DNA integrity and mitochondrial membrane potential (ΔΨm) were assessed by flow cytometry. Motility parameters were also evaluated by CASA system. A similar percentage of spermatozoa with intact plasma membrane, acrosome integrity and high ΔΨm was observed in both sperm selection methods, but only Percoll^® showed higher percentage of spermatozoa with intact plasma and acrosome membrane compared to the post-thawing group. No differences were observed in the motility, ROS, DNA fragmentation and on the in vitro embryo production in all experimental groups. In conclusion, the selection of bovine spermatozoa with Isolate^® generates spermatozoa with similar quality parameters and embryonic development compared to Percoll^® providing a suitable alternative sperm selection method for assisted reproductive techniques in this species.

The Effect of Oral Phosphodiesterase-5 Inhibitors on Sperm Parameters: A Meta-analysis and Systematic Review

OBJECTIVE

To perform a systematic review and meta-analysis to evaluate the effect of phosphodiesterase-5 (PDE5) inhibitors on sperm parameters.

METHODS

A systematic literature search was performed. Mean value and its standard deviation (mean ± standard deviation) were used to perform quantitative analysis. Statistic heterogeneity scores were assessed with the standard Cochran Q test and I2 statistic. All statistical analyses were conducted by RevMan 5.3.

RESULTS

Eleven studies embraced a total of 1317 participants and 19 subgroups or trials were included. Acute administration of PDE5 inhibitors had no effect on semen volume (mean value [MD] = 0.26; 95% confidence interval [CI]: 0.00-0.48) and sperm concentration (MD = 2.04; 95%CI: -2.95 to 7.04). However, the percentage of motile spermatozoa (MD = 7.05; 95%CI: 2.59-11.51), the percentage of total progressive motility (MD = 6.23; 95%CI: 2.43-10.04), and rapid progressive motility (MD = 3.11; 95%CI: 0.23-5.99) were increased after oral PDE5 inhibitors treatment. Interestingly, these significant changes were observed only in infertile men but not in normal patients (MD = 6.89, P < .001 vs MD = 0.67, P = .71; MD = 6.64, P = .001 vs MD = 2.11, P > .05; and MD = 3.89, P = .04 vs MD = 0.92, P = .59, respectively). The percentage of morphologically normal spermatozoa also increased in infertile men (MD = 12.15; 95%CI: 5.16-19.15). Limited evidence showed the linearity, abnormal forms of spermatozoa, as well as reproductive hormones (total testosterone, free testosterone, luteinizing hormone, and follicle-stimulating hormone) did not benefit from PDE5 inhibitors treatment.

CONCLUSION

Oral PDE5 inhibitors treatment could modestly increase the sperm motility and morphology in infertile men.

Does sperm quality and DNA integrity differ in cryopreserved semen samples from young, adult, and aged Nellore bulls?

Background

In humans, it is now well documented that rising paternal age is correlated with decreased sperm DNA integrity and embryonic developmental failures. On the other side of the coin, it is also reported that very young fathers such as teenagers carry an increased risk of adverse birth outcomes. These observations suggest that, at least in humans, there is an age window for optimal sperm DNA integrity. In bovine, little is known about sperm DNA quality in young bulls and how it evolves with age. This study aimed to fill in this gap as it may be of importance for the bovine industry to know when exactly a bull is an optimal performer for reproductive programs.

Methods

Forty Nellore bulls were divided into three age groups: 1.8 to 2 years – young bulls; 3.5 to 7 years – adult bulls; and 8 to 14.3 years – aged bulls. Three ejaculates were collected from each bull, cryopreserved and evaluated for various parameters including: computer-assisted sperm analysis (CASA), plasma membrane and acrosome integrity, mitochondrial potential, sperm nuclear protamination, DNA oxidative damage, and Sperm Chromatin Structure Assay (SCSA).

Results

We report here that young bulls presented superior values for motility, plasma and acrosomal membrane integrity, and high mitochondrial potential. However, they also presented higher values for sperm morphological abnormalities compared to adult and aged animal groups (p < 0.05). In addition, young bulls exhibited more defective protamination than older animals did. The oldest bulls showed more nuclear oxidative damage than the younger groups of bulls while both the young and aged groups were found more susceptible to DNA denaturation as revealed with the SCSA test (p < 0.05).

Conclusion

These results indicate that young bulls spermatozoa best survived the freezing procedure, followed by adult and aged bulls. However, young and aged bulls were found to be more susceptible to DNA damage, respectively caused by protamine deficiency and oxidation. Therefore, although young bulls have correct semen parameters according to classical evaluation, our results indicate that they may show some structural nuclear immaturity.

Environmental factors contributed to circannual rhythm of semen quality

We investigated whether human semen parameters present circannual rhythm or not, and whether environmental factors exert on semen quality. This retrospective study used data of patients mainly from Reproductive Medicine Center and Urology and Andrology Clinic of a general hospital in China. Sperm concentration and motility were measured by computer aided sperm analysis (CASA). Sperm morphology was scored based on the strict criteria (WHO, 2010). The Kruskal-Wallis rank test was used to investigate the relationship between semen parameters and season/month. Partial correlation coefficients were used to analyze the relationship between semen parameters and environmental factors. In this study, we found that sperm concentration and total amount per ejaculate were significantly lower in summer and higher in winter. But, sperm progressive motility and motility were significantly higher in spring and summer (from March to June), lower in autumn and winter (September and October). Unexpectedly, normal sperm morphology and mixed agglutination reaction (MAR) positive rate didn't vary along with season or month. Furthermore, temperature was negatively related to sperm concentration and total amount per ejaculate. Precipitation was positively associated with progressive motility and normal sperm morphology, but negatively related to sperm head defect percentage. The length of sunlight was positively related to progressive motility. The Air Quality Index (AQI) was positively associated with semen volume and sperm total amount per ejaculate. These suggest seasonal and monthly variation underlying some semen parameters.

Seasonal variation of human sperm cells among 4,422 semen samples: A retrospective study in Turkey

We aimed to assess the possible presence of a seasonal pattern in three parameters of semen analysis: sperm concentration, morphology, and motility as a function of the time of ejaculation and sperm production (spermatogenesis) in normal and oligozoospermic men. This retrospective study included a consecutive series of 4,422 semen samples that were collected from patients as a part of the basic evaluation of the infertile couples attending the Reproductive Endocrine Outpatient Clinic of a tertiary women's hospital in Ankara, Turkey, between January 1, 2012 and December 31, 2013. The samples were classified according to sperm concentration: ≥15 x10⁶/mL as normozoospermic samples and 4 -14.99 x10⁶/mL as oligozoospermic samples and seasonal analysis of the semen samples were carried out separately. When the data was analyzed according to the season of semen production, there was no seasonal effect on the sperm concentration. A gradual and consistent decrease in the rate of sperm with fast forward motility was observed from spring to fall with a recovery noticed during the winter. The percentage of sperms with normal morphology was found to be statistically significantly higher in the spring samples compared with the summer samples (p=0.001). Both normozoospermic and oligozoospermic semen samples appeared to have better sperm parameters in spring and winter. The circannual variation of semen parameters may be important in diagnosis and treatment desicions.

ABBREVIATIONS

WHO: World Health Organization; mRNA:messenger ribonucleic acid.

The Disappearing Sperms: Analysis of Reports Published Between 1980 and 2015

Reports regarding the changes in sperm concentration in different counties of the world are inconsistent. Furthermore, the reports that sprung up from specific epidemiological and experimental examinations did not include data of prior studies or geographical variations. The current study, following a previous report of massive fall in semen volume over the past 33 years, attempts to delineate the trend of altering sperm concentrations and factors responsible for this by reviewing article published from 1980 to July 2015 with geographic differences. The current study identified an overall 57% diminution in mean sperm concentration over the past 35 years ( r = -.313, p = .0002), which, when analyzed for each geographical region, identified a significant decline in North America, Europe, Asia, and Africa. An increasing trend of sperm concentration was identified only in Australia. The association of male age with such a trend ( R² = .979) is reported. The authors also correlated male fertility with sperm concentration. Thus, this comprehensive, evidence-based literature review aims to concisely and systematically present the available data on sperm concentration from 1980 to 2015, as well as to statistically analyze the same and correlate male health with the declining pattern of sperm count in a single scientific review to serve the scientific research zone related to reproductive health. It points to the threat of male infertility in times ahead.

Male Obesity

Many cross-sectional analyses and longitudinal studies have examined the association between adiposity and pubertal development. In addition, the impact of an increased fat mass on reproduction and fertility in human obese men and in male animal models of obesity has been studied. A trend toward earlier pubertal development and maturation in both sexes has been shown, and the notion that obese boys might progress to puberty at a slower pace than their nonobese peers can no longer be substantiated. Impaired fertility markers and reduced reproductive functions have been observed in obesity. Obesity affects both pubertal development and fertility in men.

Consistent age-dependent declines in human semen quality: a systematic review and meta-analysis

Reduced fertility typically occurs among women in their late 30s, but increasing evidence indicates that advanced paternal age is associated with changes in reproduction as well. Numerous studies have investigated age-based declines in semen traits, but the impact of paternal age on semen parameter values remains inconclusive. Using data from 90 studies (93,839 subjects), we conducted a systematic review and meta-analysis to quantify the effect of male age on seven ejaculate traits (semen volume, sperm concentration, total sperm count, morphology, total motility, progressive motility and DNA fragmentation). Age-associated declines in semen volume, percentage motility, progressive motility, normal morphology and unfragmented cells were statistically significant and results generally seemed to be robust against confounding factors. Unexpectedly, sperm concentration did not decline with increasing male age, even though we found that sperm concentration declined over time. Our findings indicate that male age needs more recognition as a potential contributor to the negative pregnancy outcomes and reduced offspring health associated with delayed first reproduction. We suggest that greater focus on collection of DNA fragmentation and progressive motility in a clinical setting may lead to better patient outcomes during fertility treatments of aging couples.

Paternal age and assisted reproductive outcomes in ICSI donor oocytes: is there an effect of older fathers?

STUDY QUESTION

Does paternal age affect semen quality and reproductive outcomes in oocyte donor cycles with ICSI?

SUMMARY ANSWER

Paternal age is associated with a decrease in sperm quality, however it does not affect either pregnancy or live birth rates in reproductive treatments when the oocytes come from donors <36 years old and ICSI is used.

WHAT IS KNOWN ALREADY

The weight of evidence suggest that paternal age is associated with decreasing sperm quality, but uncertainty remains as to whether reproductive outcomes are affected. Although developed to treat severe sperm factor infertility, ICSI is gaining popularity and is often used even in the presence of mild male factor infertility.

STUDY DESIGN, SIZE, DURATION

A retrospective cohort study spanning the period between February 2007 and June 2010. A total of 4887 oocyte donation cycles were included.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Fertilization was carried out by ICSI in all cycles included, and the semen sample used was from the male partner in all cases. The association of male age with semen parameters (volume, concentration, percentage of motile spermatozoa) was analyzed by multiple analysis of covariance. The association of male age with reproductive outcomes (biochemical pregnancy, miscarriage, ongoing pregnancy and live birth rate) was modeled by logistic regression, where the following covariates were introduced: donor age, recipient age, semen state (fresh versus frozen) and number of transferred embryos (3 and 2 versus 1).

MAIN RESULTS AND THE ROLE OF CHANCE

We identified a significant relationship between paternal age and all sperm parameters analyzed: for every 5 years of age, sperm volume decreases by 0.22 ml (P < 0.001), concentration increases by 3.1 million sperm/ml (P = 0.003) and percentage motile spermatozoa decreases by 1.2% (P < 0.001). No differences were found in reproductive outcomes (biochemical pregnancy, miscarriage, clinical pregnancy, ongoing pregnancy and live birth) among different male age groups.

LIMITATIONS, REASONS FOR CAUTION

The use of donor oocytes, while extremely useful in highlighting the role of male age in reproductive outcomes, limits the generalization of our results to a population of young women with older male partners. No data were available on perinatal and obstetrical outcomes of these pregnancies. Most (75%) cycles used frozen/thawed sperm samples which might have introduced a bias owing to loss of viability after thawing. ICSI was performed in all cycles to control for fertilization method; this technique could mask the natural fertilization rate of poorer sperm samples. Furthermore, we did not use stringent ICSI indications; and our data are therefore not generalizable to cases where only severe male factor is considered. However, male patients were of different racial background, thus allowing generalizing our results to a wider patient base.

WIDER IMPLICATIONS OF THE FINDINGS

Our study suggests that paternal age does not affect reproductive outcomes when the oocyte donor is <36 years of age, indicating that ICSI and oocyte quality can jointly overcome the lower reproductive potential of older semen.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported in part by Fundació Privada EUGIN. The authors have no conflicts of interest to declare.

The effects of advanced paternal age on fertility

Modern societal pressures and expectations over the past several decades have resulted in the tendency for couples to delay conception. While women experience a notable decrease in oocyte production in their late thirties, the effect of age on spermatogenesis is less well described. While there are no known limits to the age at which men can father children, the effects of advanced paternal age are incompletely understood. This review summarizes the current state of knowledge regarding advanced paternal age and its implications on semen quality, reproductive success and offspring health. This review will serve as a guide to physicians in counseling men about the decision to delay paternity and the risks involved with conception later in life.

Sperm parameters: paradigmatic index of good health and longevity

Since the discovery of spermatozoon by Anton van Leeuwenhoek in 1677, there has been an ever increasing understanding of its role in reproduction. Many factors adversely affect sperm quality, including varicocele, accessory gland infection, immunological factors, congenital abnormalities, and iatrogenic systemic and endocrine causes, such as diabetes mellitus, obesity, metabolic syndrome, and smoking. The mechanisms responsible for the association between poor sperm parameters and ill health may include oxidative stress, low-grade inflammation, low testosterone, and low sex-hormone-binding globulin. Oxidative stress in the testicular microenvironment may result in decreased spermatogenesis and sperm DNA damage, loss of sperm motility, and abnormal sperm morphology. Low testosterone caused by advanced age, visceral obesity, and inflammation is associated with the development of cardiovascular disease. Hence, semen analysis has an important role in the routine evaluation of idiopathic male infertility, usually manifested as low sperm counts, impaired sperm motility, or absence of sperm, and remains the most common single diagnostic tool. Several studies have shown an inverse relationship between semen quality and medical disorders. This review elucidates the effect of medical disorders and social habits on sperm quality, the mechanisms that are involved in the impairment of sperm quality, and whether or not sperm quality can be used as an index of good health and longevity in a man.

Seasonal variations of human sperm cells among 6455 semen samples: a plausible explanation of a seasonal birth pattern

OBJECTIVE

To compare the different sperm parameters according to season of the year on sperm production day and the season 70 days prior (during spermatogenesis).

STUDY DESIGN

Retrospective Andrology Laboratory data comparison. A total of 6455 consecutive semen samples were collected as part of the basic fertility evaluation of 6447 couples. According to sperm concentration, the samples were classified as Normozoospermic or Oligozoospermic and analyzed in relation to the season.

RESULTS

The sperm concentration and percentage of fast motility showed a significant decrease from spring toward summer and fall (P < .001) with recovery noticed during the winter. As well, the highest percentage of normal sperm morphology was observed during the winter months.

CONCLUSION

Seasonal sperm pattern seems to be a circannual-rhythmic phenomenon. The winter and spring semen patterns are compatible with increased fecundability and may be a plausible explanation of the peak number of deliveries during the fall.

Variability of semen parameters with time in placebo treated men

PURPOSE

We describe the variability of semen parameters with time in normal men receiving placebo. We also report the impact of season and geographic region, among other variables, on these parameters.

MATERIALS AND METHODS

Data from the placebo arms of 5 randomized, controlled trials were pooled. All trials set minimum standards for semen parameters as an eligibility criterion for entry. Semen parameters examined include volume, density, motility, total count, total motile count and morphology. Mixed model repeated measure analysis was used for statistical analysis. Coefficients of variation for each semen parameter and the percent change from baseline were calculated.

RESULTS

The mean within-subject coefficient of variation for each semen parameter ranged from a low of 10% to a high of almost 50%. The contribution of season and region to variability was negligible. The reduction in variability with an increasing number of samples per time point had decreasing returns beyond 2 samples.

CONCLUSIONS

There was considerable variation in semen parameters with time in subjects who received placebo. Variation could not be attributed to season or region. We observed a general negative trend in semen parameters in this population selected for normal baseline semen parameters, which was likely due to the placebo response or to regression toward the mean.

The effects of male age on sperm analysis by motile sperm organelle morphology examination (MSOME)

BACKGROUND

This study aimed to investigate the influence of age on sperm quality, as analysed by motile sperm organelle morphology examination (MSOME).

METHODS

Semen samples were collected from 975 men undergoing evaluation or treatment for infertility. Sperm cells were evaluated at 8400× magnification using an inverted microscope equipped with Nomarski (differential interference contrast) optics. Two forms of spermatozoa were considered: normal spermatozoa and spermatozoa with large nuclear vacuoles (LNV, defined as vacuoles occupying > 50% of the sperm nuclear area). At least 200 spermatozoa per sample were evaluated, and the percentages of normal and LNV spermatozoa were determined. The subjects were divided into three groups according to age: Group I, less than or equal to 35 years; Group II, 36-40 years; and Group III, greater than or equal to 41 years.

RESULTS

There was no difference in the percentages of normal sperm between the two younger (I and II) groups (P >0.05). The percentage of normal sperm in the older group (III) was significantly lower than that in the younger (I and II) groups (P < 0.05). There was no difference in the percentage of LNV spermatozoa between the younger (I and II) groups (P >0.05). The percentage of LNV spermatozoa was significantly higher in the older group (III) than in the younger (I and II) groups (P < 0.05). Regression analysis demonstrated a significant decrease in the incidence of normal sperm with increasing age (P < 0.05; r = -0.10). However, there was a significant positive correlation between the percentage of spermatozoa with LNV and male age (P < 0.05, r = 0.10).

CONCLUSION

The results demonstrated a consistent decline in semen quality, as reflected by morphological evaluation by MSOME, with increased age. Considering the relationship between nuclear vacuoles and DNA damage, these age-related changes predict that increased paternal age should be associated with unsuccessful or abnormal pregnancy as a consequence of fertilisation with damaged spermatozoa. Given that sperm nuclear vacuoles can be evaluated more precisely at high magnification, these results support the routine use of MSOME for ICSI as a criterion for semen analysis.

Effect of pre-freezing conditions on the progressive motility recovery rate of human frozen spermatozoa

We evaluated the effects of sperm concentration, progressive motility, sperm morphology, duration of abstinence and collection season on the progressive motility recovery rate of human frozen spermatozoa to identify characteristics that predict the progressive motility recovery rate of human frozen spermatozoa and improve the protocol for sperm collecting in sperm banks. A total of 14 190 semen samples donated at Zhejiang human sperm bank of China between September 2006 and June 2011 were collected from 1624 donors. Semen was evaluated according to WHO standard procedures for sperm concentration. Progressive motility, sperm morphology, ejaculate collection season and abstinence time were recorded. After freezing and thawing, the progressive motility was assessed. Results showed that sperm concentration, progressive motility and normal morphology were significantly associated with the progressive motility recovery rate of human frozen spermatozoa. In addition, the abstinence time and collection season also significantly affected progressive motility recovery rate. Our results indicated that sperm concentration, progressive motility and normal morphology could be valuable in predicting the progressive motility recovery rate of human frozen spermatozoa. As such, progressive motility recovery may be improved by donating semen when abstinent for 3-5 days and during seasons other than summer.

Season of birth and exceptional longevity: comparative study of american centenarians, their siblings, and spouses

This study explores the effects of month of birth (a proxy for early-life environmental influences) on the chances of survival to age 100. Months of birth for 1,574 validated centenarians born in the United States in 1880-1895 were compared to the same information obtained for centenarians' 10,885 shorter-lived siblings and 1,083 spouses. Comparison was conducted using a within-family analysis by the method of conditional logistic regression, which allows researchers to control for unobserved shared childhood or adulthood environment and common genetic background. It was found that months of birth have significant long-lasting effect on survival to age 100: siblings born in September-November have higher odds to become centenarians compared to siblings born in March. A similar month-of-birth pattern was found for centenarian spouses. These results support the idea of early-life programming of human aging and longevity.

Variation of semen parameters in healthy medical students due to exam stress

AIM

This study was aimed at investigating semen parameters that vary most in samples of healthy donors undergoing stressful examination period.

METHODS

Samples were left to liquefy in an incubator at 37 degrees C, 5% CO2 for 30 minutes before volume was measured. Concentration and motility parameters were measured by means of computer assisted semen analysis (CASA) using Sperm Class Analyzer (Microptic S.L, Madrid, Spain).

RESULTS

Sperm concentration was significantly decreased in samples donated close to the exam period as well as samples donated during the exam period when compared to samples donated at the beginning of the semester.

CONCLUSION

Stress levels of donors might prove to be clinically relevant and important when designing experiment protocols.

Are serum levels of vitamin D associated with semen quality? Results from a cross-sectional study in young healthy men

OBJECTIVE

To examine the association between low serum vitamin D concentration and estimates of male reproductive function.

DESIGN

Cross-sectional study.

SETTING

University hospital.

PATIENT(S)

From a Danish pregnancy cohort established in 1984-1987, 347 sons were selected for a study conducted in 2005-2006.

INTERVENTION(S)

Semen parameters and reproductive hormones were related to vitamin D concentrations in 307 men.

MAIN OUTCOME MEASURE(S)

Semen characteristics and reproductive hormones.

RESULT(S)

A high vitamin D level was unexpectedly associated with lower crude median total sperm count and percentage of normal morphology sperm and a high level of crude median sex hormone-binding globulin and FSH. After adjustment, the associations attenuated to nonsignificant associations, except for sex hormone-binding globulin. Additionally, adjusted free androgen index was lower at higher vitamin D levels, and men with high vitamin D had 11% (95% confidence interval, 1%-20%) lower free androgen index compared with men with low vitamin D.

CONCLUSION(S)

These results do not indicate that low vitamin D is a risk factor for poor semen quality in a population of young healthy men, but we may not have enough men with low vitamin D levels to detect an effect. New studies should include a larger proportion of vitamin D-deficient men.

Reactive oxygen species levels are independent of sperm concentration, motility, and abstinence in a normal, healthy, proven fertile man: a longitudinal study

In a longitudinal study over a period of 21 months, we demonstrated that seminal reactive oxygen species (ROS) levels are independent of sperm concentration, motility, and abstinence duration within a healthy sperm donor, although some variations were observed in ROS levels. We suggest that fluctuation in seminal ROS values may be related to physiologic or transient changes in spermatogenesis.

Variations in the birth-season effects on height attainment in the two Koreas

BACKGROUND

Previous studies have reported a consistent link between birth season and height in northern and southern hemisphere humans, creating a pattern in which spring birth cohorts are the tallest, and autumn birth cohorts are the shortest.

AIM

A previous study on heights of children born during the North Korean famine of the 1990s revealed a pattern inconsistent with other studies, suggesting that adverse living conditions during the famine may have caused the atypical result. This paper investigates this issue by comparing the anomalous finding to other Korean data.

SUBJECTS AND METHODS

The present study investigated birth season-height patterns in South Koreans and North Koreans born during the famine as well as in pre- and post-famine periods, and Colonial Koreans raised prior to the political separation of the Korean peninsula by making use of height error bars classified by birth season. The study was limited to the Korean peninsula, thus genetic factors are unlikely to have had an impact on the results.

RESULTS

With the exception of North Koreans born during the famine, all groups followed the same birth season-height pattern, a pattern consistent with other globally reported patterns. This suggests that adverse conditions during the famine are likely factors resulting in the anomalous birth season-height pattern in North Koreans born during the famine.

CONCLUSION

Birth season-height patterns of Koreans follow the typical global pattern, but extreme environmental circumstances during the North Korean food crisis appear to have significantly disrupted that pattern.

The effect of the seasons of the year on malnutrition in North Korea

North Korea's economic isolation as a consequence of its recent nuclear testing could lead to another famine. In this context, the article investigates health determinants of the last famine. Birth season is a reliable proxy for nutritional and epidemiological circumstances in early life, which in turn can systematically influence later-life health outcomes such as stature. The aim of this study is to assess the effect of birth seasons on the development of heights. Height-for-age z-scores for up to 9934 pre-school children measured in 1997 during the North Korean food crisis in the decade of the 1990 s and measured in 2002, are used for the analysis. Using these data, we have verified a number of earlier studies showing that cohorts born in winter are smaller. We have also found that cohorts born in autumn are taller. Additionally, when we control for sex, birthplace, and birth year, these calendar effects remain robust. Ignoring the humanitarian dilemma of any sort, it may be concluded that in totalitarian North Korea, Pyongyang can easily influence the biological welfare of its people by interfering with the birth calendar, in order to reduce the magnitude of a potentially upcoming famine.

The seasonality of conception

Individual data on menstrual cycles of noncontracepting women living in Western countries were used in order to verify whether the biological seasonality of conception persists after sexual behavior is controlled for. Episodes of intercourse were recorded daily, and the time of ovulation was detected by a marker We find that the seasonality of conception changes with woman's age and frequency of episodes of sexual intercourse. In particular; for women aged 27-31 having only one act of intercourse during the six most fertile days of the menstrual cycle, the seasonality of fecundability is stronger In this age group in the Northern Hemisphere, if seasonality of acts of sexual intercourse is controlled, the monthly distribution of probability of conception is bimodal, with two maxima (September and January) and two minima (December and March). When unobserved characteristics of the couples are considered, this seasonal pattern of conception persists.

Potential factors affecting semen quality in the Asian elephant (Elephas maximus)

BACKGROUND

One of the major obstacles in using artificial insemination to manage genetics of elephant population in captivity is the large variations in semen quality among ejaculates within the same and among individuals. The objectives of this study were to determine the influences of (1) age (2) seasonality (3) and circulating testosterone (SrTest), triiodothyronine (SrT3) and tetraiodothyronine (SrT4), as well as seminal (4) testosterone (SpTest), zinc (SpZn) and protein (SpTP) on semen quality in the Asian elephant

METHODS

Analyses, including motility, viability and morphology were performed in semen samples collected twice monthly from 13 elephant bulls (age range, 10-to 72-years) by manual stimulation between July 2004 and June 2005. Serum samples obtained monthly were assessed for SrTest, SrT3, SrT4, and seminal plasma samples were evaluated for, SpTest, SpZn and SpTP.

RESULTS

The highest semen quality was observed at age 23 to 43 years. Percentages of progressive motility and viable sperm were lowest at age 51 to 70 years (P < 0.05); on the other hand, sperm concentration was lowest at age 10 to 19 years (P < 0.05). Percentage of sperm with normal morphology was highest at age 23 to 43 years. The levels of SrT3, SrTest, SpTest and SpZn were lowest at age 51 to 70 years, whereas SrT4 was lowest at age 23 to 43 years. Seasonality significantly affected semen characteristics in which percentage of viable sperm and cell concentration were highest during rainy season and lowest during summer months (P < 0.05). However, percentage of sperm with normal morphology was highest in summer and lowest in rainy season (P < 0.05). Seasonality significantly influenced SrTest with elevated concentrations observed in rainy season and winter (P < 0.05).

CONCLUSION

This study indicates that age and seasonality had influence on semen characteristics in the Asian elephant. The knowledge obtained in this study will improve our understanding of the reproductive biology of this species.

Within-subject variation of seminal parameters in men with infertile marriages

As little information exists on the semen variability in infertile men, this study aimed at analysing the within-subject variability of semen from men with infertile marriages included in an intrauterine insemination (IUI) programme. Five ejaculates from each of 436 men (2180 specimens) were analysed. The within-subject coefficients of variation (CV(w)) were high for all parameters (semen volume, sperm concentration, forward motility and combined parameters), ranging from 0.73 for the total motile sperm count to 0.27 for the semen volume. Nevertheless, within-subject fluctuations were smaller than the between-subject variability, as indicated by high Intraclass Correlation Coefficient (ICC) values, which, however, significantly lowered when <or=3 samples were analysed against five samples. Neither seasonality nor the length of abstinence between 3 and 7 days significantly affected within-subject semen variability, whereas total motile sperm count was significantly and negatively affected at 2 days of abstinence. In 253 cycles of double IUI, performed in two consecutive days, semen volume and parameters including volume decreased in the second sample, but semen quality improved in most cases of oligo- and/or asthenozoospermia. Useful information for clinical purposes is provided.

Ten-year variation in semen parameters and sperm deoxyribonucleic acid integrity in a healthy fertile man

OBJECTIVE

To report parameters in semen samples and sperm DNA integrity in a healthy fertile volunteer over a 10-year period.

DESIGN

Case report.

SETTING

University-affiliated teaching hospital.

INTERVENTION(S)

None.

PATIENT(S)

Semen samples from a nonsmoking healthy male volunteer of proven fertility aged from 40 to 50 years were collected and analyzed over a decade.

MAIN OUTCOME MEASURE(S)

Semen parameters (sperm count, total sperm count, percentage of progressive motility grades a+b, morphology, and percentage of living spermatozoa) and sperm DNA integrity, measured by sperm chromatin structure assay (SCSA) and terminal uridine nick-end labeling (TUNEL) assay.

RESULT(S)

Median (min-max) value of total sperm count was 330 (126-511) million. Motility and vitality presented a median of 50% (40%-75%) and 78% (53%-92%), respectively. Among semen parameters, morphology and vitality showed the lowest within-subject coefficient of variation (CV(W)) and the total sperm count the highest (8.1% and 12.0% vs. 34.9%). Median values of DNA fragmentation index (DFI) and high DNA stainability (HDS) were 12.7% (7.9%-16.5%) and 6.5% (5.5%-8.2%), respectively. Sperm DNA fragmentation presented a median value of 8.9%, a minimum value of 1.4% and maximum value of 18.6%. Compared with TUNEL data, SCSA parameters (DFI and HDS) showed less variation over the data collection period (47.4% vs. 22.4% and 13.0%, respectively).

CONCLUSION(S)

Our data show that in this healthy fertile volunteer, semen parameters and sperm DNA integrity remained normal, and no trend was observed over the study period. More interestingly, in this subject aged from 40 to 50 years old, sperm nucleus status presented less than 20% of sperm DNA fragmentation over a decade.