Vitamin D status is not associated with reproductive parameters in young Spanish men.

BACKGROUND: Relatively low sperm count was reported among young Spanish men in 2013. Several potential culprits have been suggested as explanations for reported trends in sperm counts in Western men, including lifestyles. Although controversial, some studies suggest that semen parameters, such as low sperm motility or abnormal morphology, may be associated with low serum vitamin D levels. OBJECTIVES: To evaluate associations between semen parameters and reproductive hormones and serum 25-hydroxyvitamin D (25OHD) status in young Spanish men and to examine these associations in relation to dietary intake of vitamin D. MATERIALS AND METHODS: This cross-sectional study includes 198 university students recruited in 2010-2011 in southern Spain, who provided samples of blood and semen and food frequencies. Semen quality was evaluated by measuring volume, concentration, sperm counts, motility, and morphology, according to the WHO guidelines. Serum samples were analyzed for total 25OHD and reproductive hormones, including FSH, LH, testosterone, inhibin B, and estradiol. Dietary vitamin D intake was assessed using a validated food frequency questionnaire. Associations with semen quality and reproductive hormones were examined using linear regression, adjusting for potential confounders. RESULTS: Almost all men had adequate levels of serum vitamin D - only three men (1.5%) were vitamin D deficient (<30 nmol/L) and 17% were insufficient (<50 nmol/L). However, dietary vitamin D intakes were relatively low (below recommended 600 IU/day in 99% of men). Neither dietary intake nor serum vitamin D levels were associated with any sperm parameter or any reproductive hormone (all p ≥ 0.09). DISCUSSION: We did not observe an association between vitamin D status and any reproductive parameter in our study population. CONCLUSIONS: Our results suggest that serum vitamin D levels are sustained in Spanish men despite low dietary intake and therefore low vitamin D does not explain the poor semen quality previously observed in these young Spanish men.

Anogenital distance is associated with semen quality but not reproductive hormones in 1106 young men from the general population.

STUDY QUESTION: Is anogenital distance (AGD) associated with semen quality and reproductive hormones in men from the general population? SUMMARY ANSWER: Short AGD measured from the anus to the base of scrotum (AGDAS) was associated with reduced sperm counts and morphology but not with sperm motility or reproductive hormones. WHAT IS KNOWN ALREADY: AGD is longer in males than in females. In rodents, AGD is a well-established and sensitive marker of disruption during the masculinization programming window in utero and it has been suggested to be so in humans as well. Therefore, the average AGD would be expected to be shorter in men with poor semen quality, which some studies have confirmed while others have not. STUDY DESIGN, SIZE, DURATION: This cross-sectional population-based study was of 1106 men included between 2012 and 2016. PARTICIPANTS/MATERIALS, SETTING, METHODS: Men from the general Danish population (median age 19 years), unselected with regard to fertility status and semen quality, delivered a semen sample, had a blood sample drawn, which was analyzed for concentrations of reproductive hormones, and answered a comprehensive questionnaire. They also had a physical examination performed including determination of AGD measured as the distance between anus and scrotum (AGDAS) and penis (AGDAP). Odds ratios (OR) and 95% CI were estimated for a man having abnormal semen parameters according to the World Health Organization's reference values or a low/high concentration of reproductive hormones (defined as the lowest or highest 10%) depending on AGD. AGD was categorized in four strata: ≤10th percentile, 10th-30th percentile, 30th-50th percentile and >50th percentile. MAIN RESULTS AND THE ROLE OF CHANCE: Men with the 10% shortest AGDAS had a more than doubled risk (OR: 2.19, 95% CI: 1.40-3.42) of being in the subfertile range for either sperm concentration (<15 million/mL) or sperm morphology (<4%) compared to men with AGDAS above the median (reference). Men in the 10th-30th percentile also had an increased OR of 1.48 (95% CI: 1.06-2.08) but not men in the 30th-50th percentile (OR: 1.14, 95% CI: 0.81-1.62). AGDAP was only weakly related to semen quality. AGD was not associated with testicular volume or any of the reproductive hormones. LIMITATIONS, REASONS FOR CAUTION: Limitations include the potential non-differential misclassification of reproductive outcomes based on a single semen and blood sample and some between-examiner differences in AGD measurements which introduces noise and may result in an underestimation of observed associations. WIDER IMPLICATIONS OF THE FINDINGS: Our study of men from the general population confirmed associations between AGD and semen quality, supporting the hypothesis that AGD in humans could be a marker of fetal testicular development. This suggests that the low semen quality in Danish men may partly be explained by prenatal factors. STUDY FUNDING/COMPETING INTEREST(S): The study has received financial support from the ReproUnion (L.P.); the Research fund of Rigshospitalet, Copenhagen University Hospital (N.J.); Grants R01ES016863-04 and R01ES016863-02S4; National Institute of Environmental Health Sciences (NIEHS) and National Institute of Environmental Health Sciences grant (P30ES023515) (S.S.); the European Union (Contract numbers BMH4-CT96-0314, QLK4-CT-1999-01422, QLK4-CT-2002-00603, FP7/2007-2013, DEER Grant agreement no. 212844); the Danish Ministry of Health; the Danish Environmental Protection Agency; A.P. Møller and wife Chastine McKinney Møllers foundation; and Svend Andersens Foundation. None of the funders had any role in the study design, collection, analysis or interpretation of data, writing of the paper or publication decisions. The authors have nothing to declare. TRIAL REGISTRATION NUMBER: N/A.

First and second trimester urinary metabolic profiles and fetal growth restriction: an exploratory nested case-control study within the infant development and environment study.

BACKGROUND: Routine prenatal care fails to identify a large proportion of women at risk of fetal growth restriction (FGR). Metabolomics, the comprehensive analysis of low molecular weight molecules (metabolites) in biological samples, can provide new and earlier biomarkers of prenatal health. Recent research has suggested possible predictive first trimester urine metabolites correlating to fetal growth restriction in the third trimester. Our objective in this current study was to examine urinary metabolic profiles in the first and second trimester of pregnancy in relation to third trimester FGR in a US population from a large, multi-center cohort study of healthy pregnant women. METHODS: We conducted a nested case-control study within The Infant Development and the Environment Study (TIDES), a population-based multi-center pregnancy cohort study. We identified 53 cases of FGR based on the AUDIPOG [Neonatal growth - AUDIPOG [Internet]. [cited 29 Nov 2016]. Available from: http://www.audipog.net/courbes_morpho.php?langue=en ] formula for birthweight percentile considering maternal height, age, and prenatal weight, as well as infant sex, gestational age, and birth rank. Cases were matched to 106 controls based on study site, maternal age (± 2 years), parity, and infant sex. NMR spectroscopy was used to assess concentrations of four urinary metabolites that have been previously associated with FGR (tyrosine, acetate, formate, and trimethylamine) in first and second trimester urine samples. We fit multivariate conditional logistic regression models to estimate the odds of FGR in relation to urinary concentrations of these individual metabolites in the first and second trimesters. Exploratory analyses of custom binned spectroscopy results were run to consider other potentially related metabolites. RESULTS: We found no significant association between the relative concentrations of each of the four metabolites and odds of FGR. Exploratory analyses did not reveal any significant differences in urinary metabolic profiles. Compared with controls, cases delivered earlier (38.6 vs 39.8, p < 0.001), and had lower birthweights (2527 g vs 3471 g, p < 0.001). Maternal BMI was similar between cases and controls. CONCLUSIONS: First and second trimester concentrations of urinary metabolites (acetate, formate, trimethylamine and tyrosine) did not predict FGR. This inconsistency with previous studies highlights the need for more rigorous investigation and data collection in this area before metabolomics can be clinically applied to obstetrics.

Prenatal exposure to acetaminophen and children's language development at 30 months.

OBJECTIVE: To examine prenatal APAP exposure in relation to language development in offspring at 30 months of age. METHOD: A population-based pregnancy cohort study including 754 women who enrolled in the Swedish Environmental Longitudinal, Mother and child, Asthma and allergy (SELMA) study in pregnancy week 8-13. Two exposure measures were used: (1) maternally reported number of APAP tablets taken between conception and enrollment; (2) APAP urinary concentration at enrollment. Language development at 30 months was assessed by nurse's evaluation and parental questionnaire, including the number of words the child used (<25, 25-50 and >50). Main study outcome; parental report of use of fewer than 50 words, termed language delay (LD). RESULTS: 59.2% of women enrolled in weeks 8-13 reported taking APAP between conception and enrollment. APAP was measurable in all urine samples and urinary APAP was correlated with the number of APAP taken during pregnancy (P<0.01). Language delay was more prevalent in boys (12.6%) than girls (4.1%) (8.5% in total). Both the number of APAP tablets and urinary APAP concentration were associated with greater LD in girls but not in boys. The adjusted odds ratio (OR) for LD among girls whose mothers reported >6 vs. 0 APAP tablets was 5.92 (95% confidence interval (CI) 1.10-31.94). The OR for LD in girls whose mothers' urinary APAP was in the highest compared to the lowest quartile was 10.34 (95% CI 1.37-77.86). While it cannot be ruled out, our available data do not support confounding by indication. CONCLUSIONS: Given the prevalence of prenatal APAP use and the importance of language development, these findings, if replicated, would suggest that pregnant women should limit their use of this analgesic during pregnancy.

Anogenital distance in newborn daughters of women with polycystic ovary syndrome indicates fetal testosterone exposure.

Polycystic ovary syndrome (PCOS) affects ~7% of reproductive age women. Although its etiology is unknown, in animals, excess prenatal testosterone (T) exposure induces PCOS-like phenotypes. While measuring fetal T in humans is infeasible, demonstrating in utero androgen exposure using a reliable newborn biomarker, anogenital distance (AGD), would provide evidence for a fetal origin of PCOS and potentially identify girls at risk. Using data from a pregnancy cohort (The Infant Development and Environment Study), we tested the novel hypothesis that infant girls born to women with PCOS have longer AGD, suggesting higher fetal T exposure, than girls born to women without PCOS. During pregnancy, women reported whether they ever had a PCOS diagnosis. After birth, infant girls underwent two AGD measurements: anofourchette distance (AGD-AF) and anoclitoral distance (AGD-AC). We fit adjusted linear regression models to examine the association between maternal PCOS and girls' AGD. In total, 300 mother-daughter dyads had complete data and 23 mothers reported PCOS. AGD was longer in the daughters of women with a PCOS diagnosis compared with daughters of women with no diagnosis (AGD-AF: ß=1.21, P=0.05; AGD-AC: ß=1.05, P=0.18). Results were stronger in analyses limited to term births (AGD-AF: ß=1.65, P=0.02; AGD-AC: ß=1.43, P=0.09). Our study is the first to examine AGD in offspring of women with PCOS. Our results are consistent with findings that women with PCOS have longer AGD and suggest that during PCOS pregnancies, daughters may experience elevated T exposure. Identifying the underlying causes of PCOS may facilitate early identification and intervention for those at risk.

Comparability and reproducibility of adult male anogenital distance measurements for two different methods.

The distance from the genitals to the anus, anogenital distance, reflects androgen concentration during prenatal development in mammals. The use of anogenital distance in human studies is still very limited and the quality and consistency of measurements is an important methodological issue. The aim of this study was to assess the feasibility and reproducibility of adult male anogenital distance measurements by two different methods. All men were attending an outpatient clinic at a university hospital and underwent an andrological examination and completed a brief questionnaire. Two variants of anogenital distance [from the anus to the posterior base of the scrotum (AGDAS ) and to the cephalad insertion of the penis (AGDAP )] by two methods (lithotomy or frog-legged position) were assessed in 70 men. Within and between coefficient of variations, intra-class correlation coefficients, two-way repeated-measures analysis of variance, and scatter and Bland-Altman plots were calculated. The two methods produced similar values for AGDAP but different estimates for AGDAS . Nonetheless, the overall agreement (ICC ≥ 0.80) was acceptable for both measures. Therefore, both methods are internally consistent and adequate for epidemiological studies, and may be used depending on the available medical resources, clinical setting, and populations.

Timing of prenatal phthalate exposure in relation to genital endpoints in male newborns.

Prior studies report that penile size and male anogenital distance (AGD), sensitive markers of androgen action in utero, may be shortened by prenatal exposure to certain phthalates, including diethylhexyl phthalate (DEHP), but no human study has investigated the importance of exposure timing in these associations. The aim of this study was to examine the significance of exposure timing on the action of prenatal phthalates in particular DEHP, on male infant penile size and AGD. In The Infant Development and the Environment Study (TIDES) we measured penile width (PW) as well as anoscrotal distance (AGDAS ) and anopenile distance (AGPAP ) in newborn males. We modeled these endpoints in relation to phthalate metabolite concentrations in maternal urine samples collected in each trimester (T1, T2, and T3) in a subset of TIDES mothers (N = 168). PW was inversely associated with T2 oxidized DEHP metabolites, mono-2-ethyl-5-oxohexyl (MEOHP, ß=-0.48; 95% confidence interval, -0.93, -0.02), MEHHP (-0.48; -0.92, -0.05), mono-2-ethyl-5-carboxypentyl (MECPP, -0.51; -1.01, -0.004), although no appreciable associations were seen between PW and T1 and T3 DEHP metabolite concentrations in this subset. Concentrations of DEHP metabolites in T1 urine samples were inversely related to male AGD. For example, in T1 samples in this subset of women mono-2-ethyl-5-hydroxyhexyl (MEHHP) was inversely associated with male AGDAP (ß = -1.73; 95% confidence interval, -3.45, 0.0004). However, no appreciable associations were seen between AGD measures and any DEHP metabolite in T2 and T3 samples. These data suggest that DEHP exposure is inversely associated with AGD and PW, with PW primarily associated with T2 exposure and AGD associations seen only for T1 exposure, but no associations were found between T3 DEHP metabolites and any of these genital endpoints. These findings are consistent with data on critical windows in rodent studies, supporting the biological plausibility of these associations in humans.

Phthalate exposure and semen quality in fertile US men.

Several experimental and observational studies have demonstrated the antiandrogenicity of several phthalates. However, there is limited evidence of an association between phthalate exposure in adult life and semen quality. The aim of this study was to examine phthalate exposure during adulthood in relation to semen quality in fertile US men. This multi-center cross-sectional study included 420 partners of pregnant women who attended a prenatal clinic in one of five US cities during 1999-2001. Nine phthalate metabolites [mono (2-ethylhexyl) phthalate (MEHP), mono (2-ethyl-5-hydroxyhexyl) phthalate (MEHHP), mono (2-ethyl-5-oxohexyl) phthalate (MEOHP), and mono (2-ethyl-5-carboxypentyl) phthalate (MECPP)], as well as mono-n-butyl phthalate (MBP) and mono-isobutyl phthalate (MiBP), mono (three carboxypropyl) phthalate (MCPP), monobenzyl phthalate (MBzP), and monoethyl phthalate (MEP)] were measured in urine collected at the same time as the semen sample. We regressed natural log-transformed (ln) sperm concentration, ln(total sperm count), ln(total motile sperm count), percent motile spermatozoa, and percent spermatozoa with normal morphology on each of the nine natural log-transformed metabolite concentrations and on the molar-weighted sum of DEHP metabolites in separate models. We fit unadjusted models and models that adjusted for confounders determined a priori. In unadjusted models, ln(MiBP) was significantly and positively associated with motility and ln(MBzP) significantly negatively associated with ln(total sperm count). In adjusted linear models, urinary metabolite concentrations of DEHP, DBP, DEP, and DOP were not associated with any semen parameter. We found an inverse association between ln(MBzP) concentrations and sperm motility (ß = -1.47, 95% CI: -2.61, -0.33), adjusted for ln(creatinine concentration), geographic location, age, race, smoking status, stress, recent fever, time from sample collection and time to complete analysis. Several sensitivity analyses confirmed the robustness of these associations. This study and the available literature suggest that impacts of adult exposure to phthalates at environmental levels on classical sperm parameters are likely to be small.

Anogenital distance and reproductive parameters in young men.

The purpose of this study was to assess the relationship between anogenital distance (AGD) measures and semen quality and serum reproductive hormone levels in Caucasian young men from southern Spain. Two variants of AGD [from the anus to the posterior base of the scrotum (AGD(AS)) and to the cephalad insertion of the penis (AGD(AP))] were assessed in 215 university students. Semen parameters (semen volume, sperm concentration, total sperm counts, motility and morphology) and serum reproductive hormones (follicle stimulating hormone, luteinising hormone, inhibin B, testosterone, calculated free testosterone, oestradiol and sex hormone-binding globulin) were also determined. Associations between AGD measures and the semen quality and reproductive hormone levels were tested using multiple regression analyses. Overall, median sperm concentration was 44.0 × 10(6) ml(-1) (5th-95th percentiles: 8.9-129 × 10(6 ) ml(-1)), median total sperm count was 121 × 10(6) (18.0-400 × 10(6)), and mean (SD) testosterone level was 21.7 nmol/l (6.9). Mean (SD) AGD(AS) and AGD(AP) measures were 48.3 mm (11.6) and 128 mm (12.0) respectively. In the multivariable analysis, AGD measures were not associated with any semen parameters or any of the reproductive hormone levels, which is in contrast to results of studies of US young men or infertile men. Further research is warranted to confirm these findings.

First trimester phthalate exposure and anogenital distance in newborns.

STUDY QUESTION: Is first trimester phthalate exposure associated with anogenital distance (AGD), a biomarker of prenatal androgen exposure, in newborns? SUMMARY ANSWER: Concentrations of diethylhexyl phthalate (DEHP) metabolites in first trimester maternal urine samples are inversely associated with AGD in male, but not female, newborns. WHAT IS KNOWN ALREADY: AGD is a sexually dimorphic measure reflecting prenatal androgen exposure. Prenatal phthalate exposure has been associated with shorter male AGD in multiple animal studies. Prior human studies, which have been limited by small sample size and imprecise timing of exposure and/or outcome, have reported conflicting results. STUDY DESIGN, SIZE, DURATION: The Infant Development and the Environment Study (TIDES) is a prospective cohort study of pregnant women recruited in prenatal clinics in San Francisco, CA, Minneapolis, MN, Rochester, NY and Seattle, WA in 2010-2012. Participants delivered 787 infants; 753 with complete data are included in this analysis. PARTICIPANTS/MATERIALS, SETTING, METHODS: Any woman over 18 years old who was able to read and write English (or Spanish in CA), who was <13 weeks pregnant, whose pregnancy was not medically threatened and who planned to deliver in a study hospital was eligible to participate. Analyses include all infants whose mothers provided a first trimester urine sample and who were examined at or shortly after birth. Specific gravity (SpG) adjusted concentrations of phthalate metabolites in first trimester urine samples were examined in relation to genital measurements. In boys (N = 366), we obtained two measures of anogenital distance (AGD) (anoscrotal distance, or AGDAS and anopenile distance, AGDAP) as well as penile width (PW). In girls (N = 373), we measured anofourchette distance (AGDAF) and anoclitoral distance (AGDAC). We used multivariable regression models that adjusted for the infant's age at exam, gestational age, weight-for-length Z-score, time of day of urine collection, maternal age and study center. MAIN RESULTS AND THE ROLE OF CHANCE: Three metabolites of DEHP were significantly and inversely associated with both measures of boys' AGD. Associations (ß, 95% confidence interval (CI)) between AGDAS and (log10) SpG-adjusted phthalate concentrations were: -1.12 (-2.16, -0.07) for mono-2-ethylhexyl phthalate (MEHP), -1.43, (-2.49, -0.38) for mono-2-ethyl-5-oxohexyl phthalate (MEOHP), and -1.28 (-2.29, -0.27) for mono-2-ethyl-5-hydroxyhexyl (MEHHP). Associations were of similar magnitude for AGDAP. Associations were weaker and not statistically significant for PW. No other phthalate metabolites were associated with any genital measurement in boys. No phthalate metabolites were associated with either AGD measure in girls. LIMITATIONS, REASONS FOR CAUTION: Exposure assessment was based on a single first trimester urine sample, which may have introduced exposure misclassification. In addition, significant between-center differences suggest that this measurement is difficult to standardize. WIDER IMPLICATIONS OF THE FINDINGS: Our findings are consistent with multiple rodent studies and most human studies which were far smaller. The data we report here suggest that even at current low levels, environmental exposure to DEHP can adversely affect male genital development resulting in reproductive tract changes that may impact reproductive health later in life. These findings have important implications for public policy since most pregnant women are exposed to this ubiquitous chemical. STUDY FUNDING/COMPETING INTERESTS: Funding for TIDES was provided by the following grants from the National Institute of Environmental Health Sciences: R01ES016863-04 and R01 ES016863-02S4. The authors report no conflict of interest.

Stability of proposed biomarkers of prenatal androgen exposure over the menstrual cycle.

The prenatal hormonal milieu is widely believed to shape health later in life; however, there are considerable methodological challenges associated with measuring the in utero hormonal environment. Two potential biomarkers of prenatal androgen exposure that can be measured postnatally have been proposed: anogenital distance (AGD) and the ratio of the second to fourth digits of the hand (2D:4D). Although both measures are widely used research tools, their use in adult women may be complicated by the dramatic fluctuations in reproductive hormones across the menstrual cycle. To determine whether there is cyclical variation in these biomarkers, we conducted a longitudinal study of 12 naturally cycling, nulliparous adult women. Trained examiners assessed two measures of AGD [anus to clitoris (AGD-AC) and anus to fourchette (AGD-AF)] and 2D:4D in both hands for the duration of three menstrual cycles, taking measurements during the follicular, peri-ovulatory and luteal phases of each cycle. Despite the small sample size, longer (more masculine) AGD was associated with lower (more masculine) digit ratios, as predicted by the literature. Using multi-level linear regression models, we found that AGD and 2D:4D measurements did not differ significantly across cycle phases. AGD-AF and digit ratios in both hands were associated with age at menarche, suggesting a possible common developmental trajectory. These results demonstrate that AGD and 2D:4D are stable across the menstrual cycle. In addition, research is needed to determine how reliably these measures reflect the in utero hormonal milieu.

Sugar-sweetened beverage intake in relation to semen quality and reproductive hormone levels in young men.

STUDY QUESTION: Is consumption of sugar-sweetened beverages (SSB) associated with semen quality? SUMMARY ANSWER: Higher consumption of SSB was associated with lower sperm motility among healthy, young men. WHAT IS KNOWN ALREADY: The existing literature on the potential role of SSBs on male reproductive function is scarce and primarily focused on the relation between caffeinated beverages and semen quality. However, a rodent model suggests that SSBs may hamper male fertility. STUDY DESIGN, SIZE, DURATION: The Rochester Young Men's Study; a cross-sectional study of 189 healthy young men carried out at the University of Rochester during 2009-2010. PARTICIPANTS/MATERIALS, SETTING, METHODS: Men aged 18-22 years provided semen and blood samples, underwent a physical examination and completed a previously validated food frequency questionnaire (FFQ). Linear regression was used to analyze the association of SSBs with sperm parameters and reproductive hormone levels while adjusting for potential confounders. MAIN RESULTS AND THE ROLE OF CHANCE: SSB intake was inversely related to progressive sperm motility. Men in the highest quartile of SSB intake (≥1.3 serving/day) had 9.8 (95% CI: 1.9,17.8) percentage units lower progressive sperm motility than men in the lowest quartile of intake (<0.2 serving/day) (P, trend = 0.03). This association was stronger among lean men (P, trend = 0.005) but absent among overweight or obese men (P, trend = 0.98). SSB intake was unrelated to other semen quality parameters or reproductive hormones levels. LIMITATIONS, REASONS FOR CAUTION: As in all cross-sectional studies, causal inference is limited. An additional problem is that only single semen sample was obtained from each subject. WIDER IMPLICATIONS OF THE FINDINGS: To our knowledge, this is the first report on the relation between SSB intake and low semen quality beyond the contribution of caffeinated beverages. While our findings are in agreement with recent experimental data in rodents, more studies are required to draw conclusions on the relation of SSB with semen quality or male infertility. STUDY FUNDING/COMPETING INTEREST(S): Supported by the European Union Seventh Framework Program (Environment), 'Developmental Effects of Environment on Reproductive Health' (DEER) grant 212844. Grant P30 DK046200 and Ruth L. Kirschstein National Research Service Award T32 DK007703-16 and T32HD060454 from the National Institutes of Health. None of the authors has any conflicts of interest to declare.

Semen parameters in fertile US men: the Study for Future Families.

Establishing reference norms for semen parameters in fertile men is important for accurate assessment, counselling and treatment of men with male factor infertility. Identifying temporal or geographic variability in semen quality also requires accurate measurement of semen parameters in well-characterized, defined populations of men. The Study for Future Families (SFF) recruited men who were partners of pregnant women attending prenatal clinics in Los Angeles CA, Minneapolis MN, Columbia MO, New York City NY and Iowa City IA. Semen samples were collected on site from 763 men (73% White, 15% Hispanic/Latino, 7% Black and 5% Asian or other ethnic group) using strict quality control and well-defined protocols. Semen volume (by weight), sperm concentration (hemacytometer) and sperm motility were measured at each centre. Sperm morphology (both WHO, 1999 strict and WHO, 1987) was determined at a central laboratory. Mean abstinence was 3.2 days. Mean (median; 5th-95th percentile) values were: semen volume, 3.9 (3.7; 1.5-6.8) mL; sperm concentration, 60 (67; 12-192) × 10(6) /mL; total sperm count 209 (240; 32-763) × 10(6) ; % motile, 51 (52; 28-67) %; and total motile sperm count, 104 (128; 14-395) × 10(6) respectively. Values for sperm morphology were 11 (10; 3-20) % and 57 (59; 38-72) % normal forms for WHO (1999) (strict) and WHO (1987) criteria respectively. Black men had significantly lower semen volume, sperm concentration and total motile sperm counts than White and Hispanic/Latino men. Semen parameters were marginally higher in men who achieved pregnancy more quickly but differences were small and not statistically significant. The SFF provides robust estimates of semen parameters in fertile men living in five different geographic locations in the US. Fertile men display wide variation in all of the semen parameters traditionally used to assess fertility potential.

Latent factor regression models for grouped outcomes.

We consider regression models for multiple correlated outcomes, where the outcomes are nested in domains. We show that random effect models for this nested situation fit into a standard factor model framework, which leads us to view the modeling options as a spectrum between parsimonious random effect multiple outcomes models and more general continuous latent factor models. We introduce a set of identifiable models along this spectrum that extend an existing random effect model for multiple outcomes nested in domains. We characterize the tradeoffs between parsimony and flexibility in this set of models, applying them to both simulated data and data relating sexually dimorphic traits in male infants to explanatory variables.

Dairy food intake in relation to semen quality and reproductive hormone levels among physically active young men.

STUDY QUESTION: Is increased consumption of dairy foods associated with lower semen quality? SUMMARY ANSWER: We found that intake of full-fat dairy was inversely related to sperm motility and morphology. These associations were driven primarily by intake of cheese and were independent of overall dietary patterns. WHAT IS KNOWN ALREADY: It has been suggested that environmental estrogens could be responsible for the putative secular decline in sperm counts. Dairy foods contain large amounts of estrogens. While some studies have suggested dairy as a possible contributing factor for decreased semen quality, this finding has not been consistent across studies. STUDY DESIGN, SIZE, DURATION: The Rochester Young Men's Study (n = 189) was a cross-sectional study conducted between 2009 and 2010 at the University of Rochester. PARTICIPANTS/MATERIALS, SETTING, METHODS: Men aged 18-22 years were included in this analysis. Diet was assessed via food frequency questionnaire. Linear regression was used to analyze the relation between dairy intake and conventional semen quality parameters (total sperm count, sperm concentration, progressive motility, morphology and ejaculate volume) adjusting for age, abstinence time, race, smoking status, body mass index, recruitment period, moderate-to-intense exercise, TV watching and total calorie intake. MAIN RESULTS AND THE ROLE OF CHANCE: Total dairy food intake was inversely related to sperm morphology (P-trend = 0.004). This association was mostly driven by intake of full-fat dairy foods. The adjusted difference (95% confidence interval) in normal sperm morphology percent was -3.2% (-4.5 to -1.8) between men in the upper half and those in the lower half of full-fat dairy intake (P < 0.0001), while the equivalent contrast for low-fat dairy intake was less pronounced [-1.3% (-2.7 to -0.07; P= 0.06)]. Full-fat dairy intake was also associated with significantly lower percent progressively motile sperm (P= 0.05). LIMITATIONS, REASONS FOR CAUTION: As it was a cross-sectional study, causal inference is limited. WIDER IMPLICATIONS OF THE FINDINGS: Further research is needed to prove a causal link between a high consumption of full-fat dairy foods and detrimental effects on semen quality. If verified our findings would mean that intake of full-fat dairy foods should be considered in attempts to explain secular trends in semen quality and that men trying to have children should restrict their intake. STUDY FUNDING/COMPETING INTEREST(S): European Union Seventh Framework Program (Environment), 'Developmental Effects of Environment on Reproductive Health' (DEER) grant 212844. Grant P30 DK046200 and Ruth L. Kirschstein National Research Service Award T32 DK007703-16 from the National Institutes of Health. None of the authors has any conflicts of interest to declare.

Associations between urinary metabolites of di(2-ethylhexyl) phthalate and reproductive hormones in fertile men.

Widely used man-made chemicals, including phthalates, can induce hormonal alterations through a variety of cellular and molecular mechanisms. A number of rodent and observational studies have consistently demonstrated the anti-androgenic effect of several phthalates. However, there are only limited data on the relationship between exposure to these chemicals and reproductive hormone levels in men. All men (n=425) were partners of pregnant women who participated in the Study for Future Families in five US cities and provided urine and serum samples on the same day. Eleven phthalate metabolites were measured in urine and serum samples were analysed for reproductive hormones, including follicle-stimulating hormone, luteinizing hormone, testosterone, inhibin B and oestradiol and sex hormone-binding globulin (SHBG). Pearson correlations and parametric tests were used for unadjusted analyses, and multiple linear regression analysis was performed controlling for appropriate covariates. We observed weak or no associations with urinary phthalates other than di(2-ethylhexyl) phthalate (DEHP). All measures of testosterone [total, calculated free testosterone and the free androgen index (FAI)] were inversely correlated with the urinary concentrations of four DEHP metabolites. After adjustment by appropriate covariates, there was no longer an association between urinary DEHP metabolite concentrations and total testosterone levels; however, FAI was significantly associated with the urinary concentrations of several DEHP metabolites. SHBG was positively related to the urinary concentrations of mono(2-ethylhexyl) phthalate, but not with other DEHP metabolites, an association that was attenuated after adjustment. Our results suggest that DEHP exposure of fertile men is associated with minor alterations of markers of free testosterone.

Prenatal phthalate exposure and reduced masculine play in boys.

Foetal exposure to antiandrogens alters androgen-sensitive development in male rodents, resulting in less male-typical behaviour. Foetal phthalate exposure is also associated with male reproductive development in humans, but neurodevelopmental outcomes have seldom been examined in relation to phthalate exposure. To assess play behaviour in relation to phthalate metabolite concentration in prenatal urine samples, we recontacted participants in the Study for Future Families whose phthalate metabolites had been measured in mid-pregnancy urine samples. Mothers completed a questionnaire including the Pre-School Activities Inventory, a validated instrument used to assess sexually dimorphic play behaviour. We examined play behaviour scores (masculine, feminine and composite) in relationship to (log(10)) phthalate metabolite concentrations in mother's urine separately for boys (N = 74) and girls (N = 71). Covariates (child's age, mother's age and education and parental attitude towards atypical play choices) were controlled using multivariate regression models. Concentrations of dibutyl phthalate metabolites, mono-n-butyl phthalate (MnBP) and mono-isobutyl phthalate (MiBP) and their sum, were associated with a decreased (less masculine) composite score in boys (regression coefficients -4.53,-3.61 and -4.20, p = 0.01, 0.07 and 0.04 for MnBP, MiBP and their sum respectively). Concentrations of two urinary metabolites of di(2-ethylhexyl) phthalate (DEHP), mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP) and mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and the sum of these DEHP metabolites plus mono(2-ethylhexyl) phthalate were associated with a decreased masculine score (regression coefficients -3.29,-2.94 and -3.18, p = 0.02, 0.04 and 0.04) for MEHHP, MEOHP and the sum respectively. No strong associations were seen between behaviour and urinary concentrations of any other phthalate metabolites in boys, or between girls' scores and any metabolites. These data, although based on a small sample, suggest that prenatal exposure to antiandrogenic phthalates may be associated with less male-typical play behaviour in boys. Our findings suggest that these ubiquitous environmental chemicals have the potential to alter androgen-responsive brain development in humans.

Maternal and infant urinary phthalate metabolite concentrations: are they related?

BACKGROUND: Phthalates are synthetic chemicals that are ubiquitous in our society and may have adverse health effects in humans. Detectable concentrations of phthalate metabolites have been found in adults and children, but no studies have examined the relationship between maternal and infant phthalate metabolite concentrations. OBJECTIVE: We investigated the relationship between maternal and infant urinary phthalate metabolite concentrations. METHODS: We measured nine phthalate metabolites in urine samples from 210 mother/infant pairs collected on the same study visit day (1999-2005) and obtained demographic history from questionnaires. Using multivariate linear regression analyses, we examined the degree to which maternal urine phthalate metabolite concentration predicted infant phthalate metabolite concentration. All analyses were adjusted for infant age, creatinine concentration, and race. RESULTS: Correlation coefficients between phthalate metabolite concentrations in the urine of mothers and their infants were generally low but increased with decreasing age of infant. In multivariate analyses, mother's phthalate metabolite concentrations were significantly associated with infants' concentrations for six phthalate metabolites: monobenzyl phthalate, monoethyl phthalate, monoisobutyl phthalate, and three metabolites of di(2-ethylhexyl) phthalate: mono(2-ethylhexyl) phthalate, mono(2-ethyl-5-hydroxy-hexyl) phthalate, and mono(2-ethyl-5-oxo-hexyl) phthalate (p-values for all coefficients <0.05). DISCUSSION: Mother's urine phthalate metabolite concentration is significantly associated with infant urine phthalate metabolite concentration for six phthalate metabolites. It is plausible that shared exposures to phthalates in the immediate surrounding environment accounted for these relationships, but other unidentified sources may also contribute to infants' phthalate exposures. This study indicates the importance of further identifying infant phthalate exposures that may be distinct from maternal exposures in order to decrease overall infant phthalate exposures.

Semen quality of fertile US males in relation to their mothers' beef consumption during pregnancy.

UNLABELLED: BACKGROUND To look at possible long-term risks from anabolic steroids and other xenobiotics in beef, we examined men's semen quality in relation to their mother's self-reported beef consumption during pregnancy. METHODS: The study was carried out in five US cities between 1999 and 2005. We used regression analyses to examine semen parameters in 387 partners of pregnant women in relation to the amount of beef their mothers reported eating while pregnant. Mothers' beef consumption was also analysed in relation to the son's history of previous subfertility. RESULTS Sperm concentration was inversely related to mothers' beef meals per week (P = 0.041). In sons of "high beef consumers" (>7 beef meals/week), sperm concentration was 24.3% lower (P = 0.014) and the proportion of men with sperm concentration below 20 x 10(6)/ml was three times higher (17.7 versus 5.7%, P = 0.002) than in men whose mothers ate less beef. A history of previous subfertility was also more frequent among sons of "high beef consumers" (P = 0.015). Sperm concentration was not significantly related to mother's consumption of other meat or to the man's consumption of any meat. CONCLUSIONS These data suggest that maternal beef consumption, and possibly xenobiotics in beef, may alter a man's testicular development in utero and adversely affect his reproductive capacity.