P–741 Fetal exposure to maternal perceived stress and male reproductive function in a cohort of young adults

Study question

Is exposure to maternal perceived stress during pregnancy associated with reproductive function in adult male offspring?

Summary answer

While maternal perceived stress was prevalent in the first trimesters of pregnancy, our preliminary findings indicate little association with reproductive function in young men.

What is known already

Though studies in animals point to a connection between prenatal exposure to maternal stress and reproductive function in offspring, the underlying biological mechanisms generating a deficit remain largely unclear. In humans, the few available studies focus on exposure to bereavement or other relatively strong objective stressful life events. Our individual perception of stress is, however, more likely the sum of a complex process involving both the actual input, previous experiences, coping strategies and support from our surroundings.

Study design, size, duration

Young men and their mothers were identified through records from the Danish National Birth Cohort (DNBC). Information on exposure, i.e. maternal perceived life and emotional stress, was available from telephone interviews conducted at approximately 30 weeks of gestation (1996 to 2001). Recruitment of the young men lasted from 2017 to 2019 with 1058 participants enrolled in the final FEPOS cohort.

Participants/materials, setting, methods

Each of the 1058 men in the FEPOS cohort completed an online questionnaire and clinical examinations and provided a blood and semen sample. Information on potential pre- and postnatal confounders was retrieved from the DNBC, the Danish National Patient Register and the Danish Medical Birth Register. We applied negative binomial regression models to examine associations between maternal perceived life and emotional stress scores and semen quality, testicular size and reproductive hormones among the young men.

Main results and the role of chance

Among the 1052 young men included in preliminary analyses, the majority was exposed to maternal perceived life and/or emotional stress (76% and 83%, respectively) during the first trimesters. Life stress was predominantly related to the actual pregnancy (48%), maternal disease (19%) or occupational conditions (33%). Emotional stress included especially being touchy (58%), sad (38%) or tense (36%), covering aspects of both stress, depression and anxiety. Overall, results indicate little association between maternal stress scores and measures of semen quality and testicular size. Our study involves a large cohort with prospectively collected exposure data and direct measures of several male reproductive outcomes. We applied inverse probability weighting to account for selection into the FEPOS cohort and included a range of a priori selected maternal confounders in our models.

Limitations, reasons for caution

The male fetus may be particularly sensitive to exposure during the differentiation of reproductive tissues (8–14 weeks of gestation). Our self-reported measures of exposure cover the first 30 weeks of gestation. Absence of association may, thus, be due to a lack of specific information on timing of symptoms.

Wider implications of the findings: While our preliminary findings may appear reassuring, further efforts to improve our understanding of maternal stress in relation to fetal health and potential consequences later in life are needed.

Trial registration number

Not applicable

Birth weight for gestational age and the risk of infertility: a Danish cohort study

STUDY QUESTION

Is birth weight for gestational age associated with infertility in adulthood among men and women?

SUMMARY ANSWER

Being born small for gestational age (SGA) was associated with infertility in adulthood among men.

WHAT IS KNOWN ALREADY

Fetal growth restriction may affect fertility, but results from previous studies have been inconsistent.

STUDY DESIGN, SIZE, DURATION

In this population-based cohort study, we used data from a Danish birth cohort, including 5594 men and 5342 women born between 1984 and 1987. Information on infertility was obtained from Danish health registers during the period from the participants' 18th birthday and up until 31 December 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Participants were men and women born in two Danish municipalities, Aalborg and Odense. Information on birth weight and gestational age was obtained from birth records, and information on infertility diagnoses and fertility treatment was retrieved from the Danish National Patient Registry (NPR) and the Danish In Vitro Fertilisation (IVF) registry. Information on potential maternal confounders was obtained from questionnaires during pregnancy and was included in adjusted analyses. Logistic regression analysis was used to estimate crude and adjusted odds ratios (ORs) with 95% confidence intervals (CIs) for infertility according to birth weight for gestational age.

MAIN RESULTS AND THE ROLE OF CHANCE

Men born SGA had a 55% higher risk of being diagnosed with or treated for infertility compared to men born appropriate for gestational age (AGA) (adjusted OR = 1.55, 95% CI: 1.09-2.21). The association attenuated after exclusion of men born with hypospadias or cryptorchidism (OR = 1.37, 95% CI: 0.93-2.01). No association was found between women's birth weight for gestational age and risk of infertility (adjusted OR = 1.00, 95% CI: 0.73-1.37).

LIMITATIONS, REASONS FOR CAUTION

Estimation of gestational age is associated with some uncertainty and might have caused non-differential misclassification. The study design implicitly assumed similar distribution of reproductive and health-seeking behaviour across the groups that were compared.

WIDER IMPLICATIONS OF THE FINDINGS

Men born SGA had a higher risk of infertility. Genital malformations may account for part of the observed association, but this must be explored further.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by Health, Aarhus University. No competing interests are declared.

TRIAL REGISTRATION NUMBER

N/A.

Male alcohol consumption and fecundability

STUDY QUESTION

Does male alcohol consumption affect fecundability?

SUMMARY ANSWER

In data pooled across Danish and North American preconception cohort studies, we found little evidence of an association between male alcohol consumption and reduced fecundability.

WHAT IS KNOWN ALREADY

Experimental and clinical studies have shown that alcohol affects male reproductive physiology, mainly by altering male reproductive hormones and spermatogenesis. However, few epidemiologic studies have examined the association between alcohol consumption and male fertility.

STUDY DESIGN, SIZE, DURATION

Data were collected from two ongoing prospective preconception cohort studies: the Danish 'SnartForaeldre' (SF) study (662 couples) and the North American 'Pregnancy Study Online' (PRESTO) (2017 couples). Participants included in the current analysis were enrolled from August 2011 through June 2019 (SF) and from June 2013 through June 2019 (PRESTO).

PARTICIPANTS/MATERIALS, SETTING, METHODS

Eligible men were aged ≥18 years in SF and ≥21 years in PRESTO, in a stable relationship with a female partner and not using contraception or receiving fertility treatment. In both cohorts, alcohol consumption/serving size was self-reported as number of beers (330 mL/12 oz.), glasses of white or red wine (120 mL/4 oz. each), dessert wine (50 mL/2 oz.) and spirits (20 mL/1.5 oz.). Overall alcohol consumption was categorized as none, 1-5, 6-13 and ≥14 standard servings per week. Total menstrual cycles at risk were calculated using data from female partners' follow-up questionnaires, which were completed every 8 weeks until self-reported pregnancy or 12 menstrual cycles, whichever came first. Analyses were restricted to couples that had been trying to conceive for ≤6 cycles at study entry. Proportional probability regression models were used to compute fecundability ratios (FRs) and 95% confidence interval (CIs). We adjusted for male and female age, female partner's alcohol consumption, intercourse frequency, previous history of fathering a child, race/ethnicity, education, BMI, smoking and consumption of sugar-sweetened beverages and caffeine.

MAIN RESULTS AND THE ROLE OF CHANCE

The cumulative proportion of couples who conceived during 12 cycles of follow-up were 1727 (64.5%). The median (interquartile range) of total male alcohol consumption was 4.5 (2.0-7.8) and 4.1 (1.0-8.6) standard servings per week in the SF and PRESTO cohorts, respectively. In pooled analyses, adjusted FRs for male alcohol consumption of 1-5, 6-13 and ≥14 standard servings per week compared with no alcohol consumption were 1.02 (95% CI: 0.90-1.17), 1.10 (95% CI: 0.96-1.27) and 0.98 (95% CI: 0.81-1.18), respectively. For SF, adjusted FRs of 1-5, 6-13 and ≥14 standard servings per week compared with no alcohol consumption were 0.97 (95% CI: 0.73-1.28), 0.81 (95% CI: 0.60-1.10) and 0.82 (95% CI: 0.51-1.30), respectively. For PRESTO, adjusted FRs of 1-5, 6-13 and ≥14 standard servings per week compared with no alcohol consumption were 1.02 (95% CI: 0.88-1.18), 1.20 (95% CI: 1.03-1.40) and 1.03 (95% CI: 0.84-1.26), respectively.

LIMITATIONS, REASONS FOR CAUTION

Male alcohol consumption was ascertained at baseline only, and we did not distinguish between regular and binge drinking. In addition, we had insufficient numbers to study the effects of specific types of alcoholic beverages. As always, residual confounding by unmeasured factors, such as dietary factors and mental health, cannot be ruled out. Comorbidities thought to play a role in the reproductive setting (i.e. cancer, metabolic syndrome) were not considered in this study; however, the prevalence of cancer and diabetes was low in this age group. Findings for the highest categories of alcohol consumption (6-13 and ≥14 servings/week) were not consistent across the two cohorts.

WIDER IMPLICATIONS OF THE FINDINGS

Despite little evidence of an association between male alcohol consumption and reduced fecundability in the pooled analysis, data from the Danish cohort might indicate a weak association between reduced fecundability and consumption of six or more servings per week.

STUDY FUNDING/COMPETING INTEREST(S)

This study was supported by the National Institutes of Health (R01-HD060680, R01-HD086742, R21-HD050264, R21-HD072326, R03-HD090315), the Novo Nordisk Foundation, Oticon Fonden, Politimester J.P.N. Colind og hustru Asmine Colinds mindelegat and Erna og Peter Houtveds studielegat. PRESTO receives in-kind donations from FertilityFriend.com, Kindara.com, Swiss Precision Diagnostics and Sandstone Diagnostics for the collection of data pertaining to fertility. Dr Wise serves as a consultant on uterine leiomyomata for AbbVie.com. All other authors declare no conflict of interest.

Use of non-prescription analgesics and male reproductive function

We studied the association between intake of non-prescription analgesics and semen quality and male reproductive hormone levels in a cross-sectional study among 1493 men. The men provided one semen (n=1493) and blood sample (n=1056) and filled in questionnaires on use of non-prescription analgesics (paracetamol, NSAIDs and combination drugs (yes/no)). Adjusting for age, study and other covariates, we observed no association between intake of non-prescription analgesics and markers of semen quality. Adjusting for age and time of day of blood sampling, users of non-prescription analgesics had a 10.4% (95% confidence interval (CI) 4.0-17.1%) higher testosterone level than non-users. When we stratified by medication type, the association between analgesics and higher testosterone was observed between users of non-steroidal anti-inflammatory drugs (NSAIDs) and combination drugs but not paracetamol. This study suggests that use of non-prescription analgesics is associated with slightly higher serum testosterone levels than non-use.

Prenatal exposure to environmental chemical contaminants and asthma and eczema in school-age children

BACKGROUND

Emerging evidence suggests that prenatal or early-life exposures to environmental contaminants may contribute to an increased risk of asthma and allergies in children. We aimed to the explore associations of prenatal exposures to a large set of environmental chemical contaminants with asthma and eczema in school-age children.

METHODS

We studied 1024 mother-child pairs from Greenland and Ukraine from the INUENDO birth cohort. Data were collected by means of an interview-based questionnaire when the children were 5-9 years of age. Questions from the ISAAC study were used to define asthma, eczema, and wheeze. We applied principal components analysis (PCA) to sixteen contaminants in maternal serum sampled during pregnancy, including perfluoroalkyl substances (PFASs), metabolites of diethylhexyl (DEHP) and diisononyl (DiNP) phthalates, PCB-153, and p,p'-DDE. Scores of five principal components (PCs) explaining 70% of the variance were included in multiple logistic regression models.

RESULTS

In a meta-analysis that included both populations, the PC2 score, reflecting exposure to DiNP, was negatively associated with current eczema (OR 0.71, 95% CI 0.52-0.96). Other associations were not consistent between the two populations. In Ukrainian children, the PC3 score (DEHP) was positively associated with current wheeze (adjusted OR 1.56, 95% CI 1.03-2.37), whereas the PC5 score, dominated by perfluorooctanoic acid (PFOA), was inversely associated with current wheeze (OR 0.64, 0.41-0.99). In Greenlandic children, a negative association of PC4 (organochlorines) with ever eczema (OR 0.78, 0.61-0.99) was found.

CONCLUSIONS

We found limited evidence to support a link between prenatal exposure to environmental chemical contaminants and childhood asthma and eczema.

Non-linear association between androgen receptor CAG and GGN repeat lengths and reproductive parameters in fertile European and Inuit men

Recently the dogma that there is an inverse linear association between androgen receptor (AR) CAG and GGN polymorphisms and receptor activity has been challenged. We analysed the pattern of association between 21 male reproductive phenotypes and AR CAG/GGN repeat lengths in 557 proven-fertile men. A linear association was only found between sperm DNA fragmentation index (DFI) and CAG length, and between inhibin B and GGN length. Men with longer CAG then the reference (22-24), had higher oestradiol levels, whereas men with shorter CAG stretches had a higher DFI and a higher proportion of Fas-positive germ cells. Subjects with either short or long CAG had increased seminal levels of prostate-specific antigen and neutral α-glucosidase activity. Compared to men with the median GGN length of 23, those with shorter GGN repeats had higher levels of inhibin B, higher proportions of normal and progressive sperm, and a higher fraction of Fas-positive sperm, while men with longer GGN had higher oestradiol levels. These data indicate that at least for some markers of male reproductive function the association with CAG or GGN repeat length is curvilinear.

Maternal smoking during pregnancy and reproductive health of daughters: a follow-up study spanning two decades

STUDY QUESTION

Does in utero exposure to constituents of cigarette smoke have a programming effect on daughters' age of menarche and markers of long-term reproductive health?

SUMMARY ANSWER

In utero exposure to constituents of cigarette smoke was associated with earlier age of menarche and--to a lesser extent--changes in the testosterone profile of the young women.

WHAT IS KNOWN ALREADY

Studies observe potential effects of in utero exposure to constituents of cigarette smoke on the intrauterine formation of female gonads, but the consequences on long-term reproductive health in daughters remain unclear.

STUDY DESIGN, SIZE AND DURATION

A prospective cohort study was designed using data from 965 pregnant women enrolled prior to a routine 30th-week antenatal examination at a midwifery practice in Denmark from 1988 to 1989 and a follow-up of their 19-21-year-old daughters in 2008.

PARTICIPANTS/MATERIALS, SETTING AND METHODS

The pregnant women provided information on lifestyle factors during pregnancy, including the exact number of cigarettes smoked per day during the first and the second trimesters. A total of 438 eligible daughters were asked to complete a web-based questionnaire on reproductive health and subsequently invited to participate in a clinical examination during 2008. Of the 367 daughters (84%) who answered the questionnaire, 267 (61%) agreed to further examination. Information on menstrual pattern was provided at examination, blood samples were drawn to be analyzed for serum levels of reproductive hormones [FSH, LH, estradiol (E(2)), sex hormone-binding globulin, anti-Müllerian hormone, dehydroepiandrosterone-sulphate (DHEAS), free testosterone and free E(2)] and number of follicles (2-9 mm) were examined by transvaginal ultrasound. The daughters were divided into three exposure groups according to the level of maternal smoking during first trimester [non-exposed (reference), low-exposed (mother smoking >0-9 cigarettes/day) and high-exposed (mother smoking ≥ 10 cigarettes/day)]. Data were analyzed by multiple regression analyses in which we adjusted for potential confounders. Both crude and adjusted test for trend were carried out using maternal smoking during the first trimester as a continuous variable.

MAIN RESULTS AND THE ROLE OF CHANCE

We observed an inverse association between in utero exposure to constituents of cigarette smoke and age of menarche (P = 0.001). Daughters exposed to >0-9 cigarettes/day debuted with -2.7 [95% confidence interval (CI) -5.2 to -0.1] percentage earlier age of menarche, whereas daughters exposed to ≥ 10 cigarettes/day had -4.1 (95% CI: -6.6 to -1.5) percentage earlier age of menarche corresponding to 6.5 (95% CI: -10.7 to -2.2) months. There was a non-significant tendency towards lower levels of testosterone and DHEAS with increasing in utero exposure to constituents of cigarette smoke but no associations with follicle number, cycle length or serum levels of the other reproductive hormones were observed.

LIMITATIONS AND REASONS FOR CAUTION

We collected information on age of menarche retrospectively but the recall time was relatively short (2-10 years) and the reported values were within the normal range of Caucasians. Analyses of reproductive hormones are presented only for the group of daughters who were non-users of hormonal contraceptives because users were excluded, leaving only a low number of daughters available for the analyses (n = 75), as reflected in the wide CIs. The analyses of hormones were further adjusted for menstrual phase at time of clinical examination (follicular, ovulation and luteal phase) because blood samples were not collected on a specific day of the menstrual cycle.

WIDER IMPLICATIONS OF THE FINDINGS

This study supports the limited evidence of an inverse association between maternal smoking during pregnancy and age of menarche and further addresses to what extent reproductive capacity and hormones may be programmed by maternal smoking during pregnancy. A trend toward earlier maturation of females is suggested to have implications on long-term reproductive function.

STUDY FUNDING/COMPETING INTEREST(S)

Supported by a scholarship from The Lundbeck Foundation (R93-A8476). No conflict of interest declared.

Male-mediated infertility in sons of building painters and gardeners: a nationwide register-based follow-up study

AIM

To investigate whether sons of gardeners and building painters have increased risk of infertility in comparison with sons of bricklayers, carpenters and electricians.

METHODS

Participants were men born 1965-1984 in Denmark whose fathers the year before birth had worked as gardeners, painters, bricklayers, carpenters or electricians (N=22,978). Cases of infertility were identified by Danish registers, and participants were followed-up for up to 24 years after their 20th birthday.

RESULTS

Sons of gardeners did not have increased risk of infertility. Hazard ratios for sons of painters fluctuated around the null in main analyses but were 1.6 (98% CI: 1.0-2.5) and 1.7 (95% CI: 0.9-3.2) in the subset of participants with smallest risk of paternal exposure misclassification.

CONCLUSIONS

Working as gardener or building painter was not related to increased risk of infertility among the next generation of males in main analyses. However, inherent limitations in data may have attenuated true associations.

Maternal alcohol consumption during pregnancy and semen quality in the male offspring: two decades of follow-up

BACKGROUND

Concurrent alcohol exposure has been associated with reduced fecundity, but no studies have estimated the effect of prenatal alcohol exposure on male fecundity. The aim of this study was to investigate the association between maternal alcohol consumption during pregnancy, semen quality and levels of reproductive hormones in young, adult men.

METHODS

From a Danish pregnancy cohort established in 1984-1987, 347 sons were selected for a follow-up study conducted in 2005-2006. Semen and blood samples were analyzed for conventional semen characteristics and reproductive hormones, respectively, and results were related to prospectively self-reported information on maternal alcohol consumption during pregnancy.

RESULTS

The sperm concentration decreased with increasing prenatal alcohol exposure. The adjusted mean sperm concentration among sons of mothers drinking >or=4.5 drinks per week during pregnancy was 40 (95% CI: 25-60) millions/ml. This concentration was approximately 32% lower compared with men exposed to <1.0 drink per week, who had a sperm concentration of 59 (95% CI: 44-77) millions/ml. The semen volume and the total sperm count were also associated with prenatal alcohol exposure; sons prenatally exposed to 1.0-1.5 drinks per week had the highest values. No associations were found for sperm motility, sperm morphology or any of the reproductive hormones, including testosterone.

CONCLUSIONS

These results indicate that prenatal exposure to alcohol may have a persisting adverse effect on Sertoli cells, and thereby sperm concentration. If these associations are causal they could explain some of the reported differences between populations and long-term changes in semen quality.

Menstrual cycle characteristics in European and Inuit women exposed to persistent organochlorine pollutants

BACKGROUND

Previous inconsistent results suggest that menstrual cycles may be disturbed by exposure to polychlorinated biphenyls (PCBs) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (DDE).

METHODS

Information on menstrual cycle characteristics were obtained by questionnaires, and PCB and DDE were measured in serum samples from a total of 1494 women from Greenland, Swedish fishermen's wives, and inhabitants of Warsaw in Poland and Kharkiv in Ukraine.

RESULTS

No consistent effects of PCB and DDE exposure on menstrual cycle characteristics were observed across populations. Within populations, we observed increased risks of short cycles (< or =24 days) among Swedish fishermen's wives exposed to high levels of PCB [odds ratio (OR) 2.5, confidence interval (CI) 1.2-5.1], and increased risk of long cycles (> or =32 days) among Polish women exposed to high levels of DDE (OR 3.1, CI 1.1-8.6). However, in Greenland it seemed that high levels of PCB or DDE were protective against long menstrual cycles (OR 0.7 CI 0.5-0.96 and OR 0.7 CI 0.5-0.99, respectively).

CONCLUSIONS

It is unlikely that exposure to PCB and DDE is a main cause of menstrual disturbances. Genetic differences or dietary factors may be involved in the non-homogenous associations of organochlorine exposure and menstrual cycle between countries.

Relationships between sperm DNA fragmentation, sperm apoptotic markers and serum levels of CB-153 and p,p′-DDE in European and Inuit populations

Persistent organochlorine pollutants (POPs) are suspected to interfere with hormone activity and the normal homeostasis of spermatogenesis. We investigated the relationships between sperm DNA fragmentation, apoptotic markers identified on ejaculated spermatozoa and POP levels in the blood of 652 adult males (200 Inuits from Greenland, 166 Swedish, 134 Polish and 152 Ukrainian). Serum levels of 2, 2′, 4, 4′, 5, 5′-hexachlorobiphenyl (CB-153), as a proxy of the total POP burden, and of 1,1-dichloro-2,2-bis(p-chlorophenyl)-ethylene (p,p′-DDE), as a proxy of the total DDT exposure were determined. Sperm DNA fragmentation was measured by using the TUNEL assay, whereas immunofluorescence methods were utilized for detecting pro-apoptotic (Fas) and anti-apoptotic (Bcl-xL) markers. Both TUNEL assay and apoptotic markers were statistically differed across the four populations. No correlation between neither sperm DNA fragmentation nor apoptotic sperm parameters and the large variations in POPs exposure was observed for the separate study groups. However, considering the European populations taken together, we showed that both %TUNEL positivity and Bcl-xL were related to CB-153 serum levels, whereas our study failed to demonstrate any relations between DDE and %TUNEL positivity and apoptotic sperm biomarkers (Fas and Bcl-xL) in any region or overall regions. These results suggest that CB-153 and related chemicals might alter sperm DNA integrity and Bcl-xL levels in European adult males, but not in the highly exposed Inuit men. Additional issues (genetic background, lifestyle habits and characterization of total xeno-hormonal activities) need to be investigated in order to fully assess the population variations observed.

Is smoking a risk factor for decreased semen quality? A cross-sectional analysis

BACKGROUND

Previous studies suggest a deleterious effect of cigarette smoking on semen quality, but their results have not been consistent. We studied the association between current smoking and semen characteristics and hormonal levels in a large group of healthy men.

METHODS

From 1987 to 2004, seven separate occupational or environmental semen quality studies were co-ordinated by our department. A total of 2562 men participated, each providing semen and blood sample and answering a questionnaire about lifestyle and factors related to health. Appropriate semen and smoking data were available for 2542 men.

RESULTS

Adjusting for study, age and other covariates, we observed an inverse dose-response relation between smoking and semen volume, total sperm count and percentage motile sperm. Heavy smokers had a 19% lower sperm concentration than non-smokers. We found a positive dose-response relationship between smoking and testosterone, LH and the LH/free testosterone ratios.

CONCLUSION

Current smoking in adult life moderately impairs the semen quality. It is well known that semen quality is associated to fecundity. Therefore, it would be sensible to advise men to abstain from smoking to avoid decreased fecundity.

Time to pregnancy as a function of male and female serum concentrations of 2,2'4,4'5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE)

BACKGROUND

Persistent organochlorine pollutants (POP) may affect both the female and male reproductive system in animals as well as in humans.

METHODS

Blood samples were collected from pregnant women and their partners from Greenland, Warsaw and Kharkiv, and from a cohort of Swedish fishermen's wives. Blood samples were analysed for 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and 1,1-dichloro-2,2-bis (p-chlorophenyl)-ethylene (p,p'-DDE). Information on the participants' fertility, measured as time to pregnancy (TTP), was collected. In total, 778 men and 1505 women were included in the analyses.

RESULTS

The data from Warsaw, Kharkiv and the Swedish fishermen's wives indicated no effect of either male or female exposure to POP on TTP. However, among men and women from Greenland, there seemed to be an association between serum concentrations of CB-153 and p,p'-DDE and prolonged TTP. Due to the strong intra-individual correlation between CB-153 and p,p'-DDE in the Greenlandic population, it was not possible to determine whether the risk was associated with CB-153 or p, p'-DDE or was an interaction between the two compounds.

CONCLUSIONS

The overall results of the present study create a somewhat ambiguous pattern, but give some support to the idea that dietary POP exposure might be harmful for couple fertility.

Exposure to PCB and p, p′-DDE in European and Inuit populations: impact on human sperm chromatin integrity

BACKGROUND

Persistent organochlorine pollutants (POP), such as polychlorinated biphenyls (PCB) and dichlorodiphenyldichloroethylene (p, p'-DDE), are widely found in the environment and considered potential endocrine-disrupting compounds (EDC). Their impact on male fertility is still unknown.

METHODS

To explore the hypothesis that POP is associated with altered sperm chromatin integrity, a cross-sectional study involving 707 adult males (193 Inuits from Greenland, 178 Swedish fishermen, 141 men from Warsaw, Poland, and 195 men from Kharkiv, Ukraine) was carried out. Serum levels of 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153), as a proxy of the total PCB burden, and of p,p'-DDE were determined. Sperm chromatin structure assay (SCSA) was used to assess sperm DNA/chromatin integrity.

RESULTS

We found a strong and monotonically increasing DNA fragmentation index with increasing serum levels of CB-153 among European but not Inuit men, reaching a 60% higher average level in the highest exposure group. No significant associations were found between SCSA-derived parameters and p, p'-DDE serum concentrations.

CONCLUSION

These results suggest that human dietary PCB exposure might have a negative impact on the sperm chromatin integrity of adult males but additional issues, including differences in the genetic background and lifestyle habits, still need to be elucidated.

Fecundability according to male serum inhibin B—a prospective study among first pregnancy planners

BACKGROUND

New biological markers of male fecundity are needed for use in large-scale epidemiological studies. We studied the association between male inhibin B and fecundability.

METHODS

Four hundred and thirty Danish couples without previous reproductive experience were followed from termination of contraception until pregnancy or for a maximum of six menstrual cycles. At enrolment we obtained semen samples (n = 418) and blood samples to measure reproductive hormones, including inhibin B (n = 343).

RESULTS

The fecundability odds ratio for an increment of male inhibin B by 1 log pg/ml was 1.428 (95% confidence interval 1.022-1.994), adjusted for factors influencing the crude estimate. Only inhibin B values below 100 pg/ml were strongly related to fecundability. We designed a receiver operating characteristic curve based on the 29 males with serum inhibin B #100 pg/ml. The area under the curve (AUC) for inhibin B was 0.787 and the corresponding AUCs for sperm density and FSH were 0.913 and 0.800, respectively.

CONCLUSION

Serum inhibin B may be a reliable marker of male fecundity for epidemiological research and may have some advantages over sperm density. Our findings do not support the replacement of sperm density by male inhibin B when obtaining sperm data is an option.

Lower sperm counts following prenatal tobacco exposure

BACKGROUND

Recent findings have indicated that prenatal exposure to tobacco smoke may cause lower sperm concentration in ejaculates of adult men. To extend the research on this hypothesis we investigated the dose-dependency of the association, controlling for other prenatal exposures.

METHODS

From 1987 to 1996, four separate occupational semen studies were conducted at three centres in Denmark. A total of 945 men provided semen and blood samples, and information on reproductive and lifestyle factors. In 2004, we collected data on the maternal smoking habits during pregnancy from 522 mothers of the participating men.

RESULTS

Adjusting for study subgroup, abstinence time and other factors, we found statistically non-significant differences in mean sperm concentrations: 65.0 x 10(6)/ml [95% confidence interval (CI) 51, 81] among sons of non-smokers; 59.1 x 10(6)/ml (95% CI 46, 75) among sons of mothers who had smoked 1-10 cigarettes/day; and 57.7 x 10(6)/ml (95% CI 40, 81) among those whose mothers had smoked >10 cigarettes/day. The former group had a higher odds ratio (OR) for oligozoospermia (sperm concentration < or =20 x 10(6)/ml) of 1.5 (95% CI 0.9, 2.8), the latter group an OR of 2.6 (95% CI 1.2, 5.8).

CONCLUSION

We observed a dose-dependent association between prenatal tobacco exposure, lower sperm concentration and higher risk of oligozoospermia.

Sexual characteristics are altered by 4-tert-octylphenol and 17beta-estradiol in the adult male guppy (Poecilia reticulata)

Endocrine-disrupting chemicals (EDCs) are believed to interfere with animal reproduction, but only few biomarkers above the cellular level have been developed to assess the adverse effects of these chemicals. Using the guppy (Poecilia reticulata) as a model organism, studies have been undertaken with the object of comparing biomarker responses to EDCs at increasing levels of biological complexity. Short-term exposure to the xenoestrogen 4-tert-octylphenol and the natural estrogen 17beta-estradiol (E2) changed important sexual characteristics in the adult male guppy. Both compounds increased the number of sperm cells in the ejaculates, reduced the area and color intensity of the sexually attractive orange spots, and inhibited testis growth. In the case of E2, the effects on sperm count and coloration were still evident after 3 months of recovery in clean water. Preliminary results on male reproductive capability demonstrated that treated males produced fewer offspring than untreated fish, indicating an impairment of reproduction itself.

Intravenously and topically applied magnesium in the prevention of arterial thrombosis

Magnesium (Mg) has been shown to reduce platelet aggregation both in vitro and ex vivo, and this antiplatelet effect may be advantageous in the prevention of arterial thrombosis. Previous animal studies have shown an antithrombotic effect of Mg also in vivo, but mainly with higher Mg concentrations ( approximately 3.0-4.0 mM). The objectives of the present study were to evaluate the antithrombotic effect of (1) intravenous Mg at a lower and clinically more relevant concentration and (2) topically applied Mg. The study comprised 30 male rats, randomly assigned into 3 groups: (1) placebo group, (2) intravenous Mg group, and (3) topical Mg group. A thrombogenic lesion was established by making a standardised arteriotomy in the right femoral artery. The vessel was transilluminated and thrombus formation was visualised dynamically by in vivo microscopy and recorded on videotapes. Thrombus area was measured after ended experiment by computer-assisted image analysis. Intravenously administered Mg, elevating the S-Mg level to 2.2 mmol/L, significantly reduced the mean thrombus area (p<0.05) compared to the control group. Topically applied Mg significantly decreased the maximum thrombus area, without any increase in S-Mg level (p<0.05). The Mg-treated groups showed no increase in bleeding complications. A transient fall in blood pressure was seen in the systemic Mg group, but blood pressures were not significantly different between any of the groups at the end of the experiment. In conclusion, topically as well as intravenously infused Mg reduce arterial thrombus formation in this in vivo rat model without compromising haemostasis.

Microvascular damage secondary to thromboembologenic arterial injury--a new experimental model

BACKGROUND AND AIMS

The isolated rat cremaster model is used extensively for evaluating the microcirculation secondary to arterial injury. Current techniques, however, do not allow for assessment of injury and effect within the same animal. The purpose of this study was to develop a model incorporating the following points: visualization of the upstream arterial injury and the downstream microvascular damage in the same animal, analysis of capillary density by randomization of measuring windows throughout the cremaster muscle, and simplification of the arterial injury.

MATERIALS AND METHODS

Thirteen male Wistar rats were randomized into two groups. In group I, the entire isolation of the cremaster muscle was performed, without arterial damage. In group II, arterial damage consisting of a standardized pinch was applied to the feeding vessel.

RESULTS AND CONCLUSIONS

It was possible to produce a simplified arterial injury and visualize the resulting downstream microvascular damage in the same animal, in a quantitative and randomized fashion. In group I, no thrombus formation was seen. In group II, all animals produced an embolizing arterial thrombus, which was dynamic within the first hour of observation. Capillary density was reduced from 6.5 to 3.5 capillaries/measuring window within the first hour after arterial thromboembolism.