Fecundity, the biologic capacity to reproduce, is essential for the health of individuals and is, therefore, fundamental for understanding human health at the population level. Given the absence of a population (bio)marker, fecundity is assessed indirectly by various individual-based (e.g. semen quality, ovulation) or couple-based (e.g. time-to-pregnancy) endpoints. Population monitoring of fecundity is challenging, and often defaults to relying on rates of births (fertility) or adverse outcomes such as genitourinary malformations and reproductive site cancers. In light of reported declines in semen quality and fertility rates in some global regions among other changes, the question as to whether human fecundity is changing needs investigation. We review existing data and novel methodological approaches aimed at answering this question from a transdisciplinary perspective. The existing literature is insufficient for answering this question; we provide an overview of currently available resources and novel methods suitable for delineating temporal patterns in human fecundity in future research.

Spillover effects in health service use may represent an important externality of individual treatment decisions and are important for understanding the consequences of interventions to improve access to health care. This study is the first to our knowledge to examine causal spillover effects for mental health service use. We exploit the natural experiment of first-year student housing assignments at two universities using survey data that we collected. When the peer group is defined at the roommate level, we do not find any spillover effects on service use. When the peer group is defined at the hall level, we find positive spillover effects--peers' service use increases one's own service use--and this effect is driven by individuals with prior experience with mental health services. We also find some evidence that the mechanism behind this effect is improved beliefs about treatment effectiveness.

Objective: Examine relationships between weight-related factors and weight status, body dissatisfaction, chronic health conditions, and quality of life across sexual orientation and gender. Methods: Two- and four-year college students participated in the College Student Health Survey (n = 28,703; 2009–2013). Risk differences were calculated to estimate relationships between behavioral profiles and weight status, body satisfaction, diagnosis of a chronic condition, and quality of life, stratified by gender and sexual orientation. Four behavioral profiles, characterized as “healthier eating habits, more physically active,” “healthier eating habits,” “moderate eating habits,” and “unhealthy weight control,” were utilized based on latent class analyses, estimated from nine weight-related behavioral survey items. Results: Sexual orientation differences in weight and quality of life were identified. For example, sexual minority groups reported significantly poorer quality of life than their heterosexual counterparts (females: 22.5%–38.6% (sexual minority) vs. 19.8% (heterosexual); males: 14.3%–26.7% (sexual minority) vs. 11.8% (heterosexual)). Compared with the “healthier eating habits, more physically active” profile, the “unhealthy weight control” profile was associated with obesity, poor body satisfaction, and poor quality of life in multiple gender/sexual orientation subgroups. Conclusions: Interventions are needed to address obesity, body dissatisfaction, and poor quality of life among sexual minority college students.

Purpose. To identify and describe homogenous classes of male college students based on their weight-related behaviors (e.g., eating habits, physical activity, and unhealthy weight control) and to examine differences by sexual orientation. Design. Study design was a cross-sectional sample of 2- and 4-year college students. Setting. Study setting was forty-six 2- and 4-year colleges in Minnesota. Subjects. Study subjects comprised 10,406 college males. Measures. Measures were five categories of sexual orientation derived from self-reported sexual identity and behavior (heterosexual, discordant heterosexual [identifies as heterosexual and engages in same-sex sexual behavior], gay, bisexual, and unsure) and nine weight-related behaviors (including measures for eating habits, physical activity, and unhealthy weight control). Analysis. Latent class models were fit for each of the five sexual orientation groups, using the nine weight-related behaviors. Results. Overall, four classes were identified: "healthier eating habits" (prevalence range, 39.4%-77.3%), "moderate eating habits" (12.0%-30.2%), "unhealthy weight control" (2.6%-30.4%), and "healthier eating habits, more physically active" (35.8%). Heterosexual males exhibited all four patterns, gay and unsure males exhibited four patterns that included variations on the overall classes identified, discordant heterosexual males exhibited two patterns ("healthier eating habits" and "unhealthy weight control"), and bisexual males exhibited three patterns ("healthier eating habits," "moderate eating habits," and "unhealthy weight control"). Conclusion. Findings highlight the need for multibehavioral interventions for discordant heterosexual, gay, bisexual, and unsure college males, particularly around encouraging physical activity and reducing unhealthy weight control behaviors.

BACKGROUND: Little is known about the physical activity patterns of Somali adolescents. This study compared time spent in moderate-to-vigorous physical activity (MVPA) and participation in specific physical activities among Somali, other Non-Hispanic black and white adolescents. METHODS: A subsample of 1,268 adolescents (mean age= 14.6) who completed surveys as part of the EAT 2010 (Eating and Activity in Teens) study was included in analyses. Gender-stratified linear and logistic regressions, controlling for body mass index and demographic characteristics, were conducted to estimate mean weekly hours of self-reported MVPA and mean weekly hours and prevalence of engagement in each of 26 physical activities assessed by ethnic/racial group. RESULTS: Somali girls had lower mean MVPA hours than their peers; however, no differences were found for Somali boys. Involvement in most activities was similar for Somali and other groups, but some differences were observed. For example, Somali youth were more likely to play soccer than their same-sex other black peers (boys: 52.4% vs. 20.4%; girls: 34.6% vs. 14.6%; P < .05). Somali girls also engaged in more hours per week of soccer than their black or white peers. CONCLUSIONS: Activities for which Somali youth indicated higher involvement may be particularly relevant for culturally-tailored physical activity programming.