What is the relationship between body size, physical activity and semen parameters among male partners of couples attempting to become pregnant? Overweight and obesity are associated with a higher prevalence of low ejaculate volume, sperm concentration and total sperm count. Higher BMI is associated with impaired semen parameters, while increasing waist circumference (WC) is also associated with impaired semen parameters in infertile men. Data from the Longitudinal Investigation of Fertility and the Environment (LIFE) Study were utilized. The LIFE study is a population-based prospective cohort of 501 couples attempting to conceive in two geographic areas (Texas and Michigan, USA) recruited in 2005–2009. Couples were recruited from four counties in Michigan and 12 counties in Texas to ensure a range of environmental exposures and lifestyle characteristics. In person interviews were conducted to ascertain demographic, health and reproductive histories followed by anthropometric assessment. We categorized BMI (kg/m²) as <25.0 (underweight and normal), 25.0–29.9 (overweight) 30.0–34.9 (obese, class I) and ≥35 (obese, class II) for analysis. Data were available for analysis in 468 men (93% participation), with a mean ± SD age of 31.8 ± 4.8 years, BMI of 29.8 ± 5.6 kg/m² and WC of 100.8 ± 14.2 cm. The majority of the cohort (82%) was overweight or obese with 58% reporting physical activity <1 time/week. The median sperm concentration for the men in the cohort was 60.2 M/ml with 8.6% having oligospermia (<15 M/ml). When examining semen parameters, ejaculate volume showed a linear decline with increasing BMI and WC (P < 0.01). Similarly, the total sperm count showed a negative linear association with WC (P < 0.01). No significant relationship was seen between body size (i.e. BMI or WC) and semen concentration, motility, vitality, morphology or DNA fragmentation index. The percentage of men with abnormal volume, concentration and total sperm increased with increasing body size (P < 0.05). No relationship between physical activity and semen parameters was identified. Our cohort was largely overweight and sedentary, which may result in limited external validity, i.e. generalizability. The lack of physical activity did preclude examination of exercise more frequently than once per week, thus our ability to examine more active individuals is limited. Body size (as measured by BMI or WC) is negatively associated with semen parameters with little influence of physical activity. Our findings are the first showing a relationship between WC and semen parameters in a sample of men without known infertility. Given the worldwide obesity epidemic, further study of the role of weight loss to improve semen parameters is warranted. Supported by the Intramural Research Program of the Eunice Kennedy Shriver National Institute of Child Health and Human Development (Contracts #N01-HD-3-3355, N01-HD-3-3356 and N01-HD-3-3358). There are no competing interests.

How has the mean paternal age in the USA changed over the past 4 decades? The age at which men are fathering children in the USA has been increasing over time, although it varies by race, geographic region and paternal education level. While the rise in mean maternal age and its implications for fertility, birth outcomes and public health have been well documented, little is known about paternal characteristics of births within the USA. A retrospective data analysis of paternal age and reporting patterns for 168 867 480 live births within the USA since 1972 was conducted. All live births within the USA collected through the National Vital Statistics System (NVSS) of the Centers for Disease Control and Prevention (CDC) were evaluated. Inverse probability weighting (IPW) was used to reduce bias due to missing paternal records. Mean paternal age has increased over the past 44 years from 27.4 to 30.9 years. College education and Northeastern birth states were associated with higher paternal age. Racial/ethnic differences were also identified, whereby Asian fathers were the oldest and Black fathers were the youngest. The parental age difference (paternal age minus maternal age) has decreased over the past 44 years. Births to Black and Native American mothers were most often lacking paternal data, implying low paternal reporting. Paternal reporting was higher for older and more educated women. Although we utilized IPW to reduce the impact of paternal reporting bias, our estimates may still be influenced by the missing data in the NVSS. Paternal age is rising within the USA among all regions, races and education levels. Given the implications for offspring health and demographic patterns, further research on this trend is warranted. No funding was received for this study and there are no competing interests. N/A.

We studied the patient risk factors that promote urethroplasty failure. Records of patients who underwent urethroplasty at the University of California, San Francisco Medical Center between 1995 and 2004 were reviewed. Cox proportional hazards regression analysis was used to identify multivariate predictors of urethroplasty outcome. Between 1995 and 2004, 443 patients of 495 who underwent urethroplasty had complete comorbidity data and were included in analysis. Median patient age was 41 years (range 18 to 90). Median followup was 5.8 years (range 1 month to 10 years). Stricture recurred in 93 patients (21%). Primary estimated stricture-free survival at 1, 3 and 5 years was 88%, 82% and 79%. After multivariate analysis smoking (HR 1.8, 95% CI 1.0-3.1, p = 0.05), prior direct vision internal urethrotomy (HR 1.7, 95% CI 1.0-3.0, p = 0.04) and prior urethroplasty (HR 1.8, 95% CI 1.1-3.1, p = 0.03) were predictive of treatment failure. On multivariate analysis diabetes mellitus showed a trend toward prediction of urethroplasty failure (HR 2.0, 95% CI 0.8-4.9, p = 0.14). Length of urethral stricture (greater than 4 cm), prior urethroplasty and failed endoscopic therapy are predictive of failure after urethroplasty. Smoking and diabetes mellitus also may predict failure potentially secondary to microvascular damage.

What is the relationship between semen parameters and mortality in men evaluated for infertility? Among men undergoing an infertility evaluation, those with abnormal semen parameters have a higher risk of death, suggesting a possible common etiology between infertility and mortality. Conflicting data exist that suggest either an inverse relationship or no relationship between semen quality and mortality. A study cohort was identified from two centers, each specializing in infertility care. In California, we identified men with data from 1994 to 2011 in the Stanford Reproductive Endocrinology and Infertility semen database. In Texas, we identified men with data from 1989 to 2009 contained in the andrology database at the Baylor College of Medicine Special Procedures Laboratory who were evaluated for infertility. Mortality was determined by data linkage to the National Death Index or Social Security Death Index. Comorbidity was estimated based on calculation of the Charlson Comorbidity Index or Centers for Medicare & Medicaid Services-Hierarchical Condition Categories Model. In all, 11 935 men were evaluated for infertility from 1989 to 2011. During 92 104 person years of follow-up, 69 of 11 935 men died (0.58%). The mean age at infertility evaluation was 36.6 years with a mean follow-up of 7.7 years. Compared with the general population, men evaluated for infertility had a lower risk of death with 69 deaths observed compared with 176.7 expected (Standardized mortality rate 0.39, 95% CI 0.30–0.49). When stratified by semen parameters, however, men with impaired semen parameters (i.e. male factor infertility) had significantly higher mortality rates compared with men with normal parameters (i.e. no male factor infertility). Low semen volume, sperm concentration, sperm motility, total sperm count and total motile sperm count were all associated with higher risk of death. In contrast, abnormal sperm morphology was not associated with mortality. While adjusting for current health status attenuated the association between semen parameters and mortality, men with two or more abnormal semen parameters still had a 2.3-fold higher risk of death compared with men with normal semen (95% CI 1.12–4.65). Our cohort represents infertile men, which may limit generalizability. As comorbidity relied on administrative data, granular information on each man regarding infertility diagnosis and lifestyle factors was unavailable. Men with impaired semen parameters have an increased mortality rate in the years following an infertility evaluation suggesting semen quality may provide a marker of health. This study is supported in part by P01HD36289 from the Eunice Kennedy Shriver National Institute for Child Health and Human Development, National Institutes of Health (to D.J.L. and L.I.L.). The project was also partially supported by an NIH CTSA award number UL1 RR025744. None of the authors has any conflict of interest to declare.