Timing of spermarche and menarche are associated with physical activity and sedentary behavior among Korean adolescents.
Lee, E., Pabayo, R., & Kawachi, I.
Osong Public Health and Research Perspectives, August, 2016

Abstract
Objectives This study examined the timing of menarche and spermarche and their associations with physical activity (PA) and sedentary behavior (SB) after controlling for body mass index (BMI). Methods Multiple logistic regression analyses were conducted to determine whether the timing of menarche in girls and spermarche in boys is associated with PA and SB independent of BMI in a nationally representative sample of Korean adolescents (13–18 years; N = 74,186). Results After controlling for age, family economic status, and BMI, early timing of spermarche among boys was associated with a higher likelihood of engaging in PA and a lower likelihood of engaging in SB for < 2 hours during weekdays. By contrast, boys with late timing of spermarche were less likely to engage in PA and more likely to engage in SB for < 2 hours. Among girls, early or late timing of menarche was associated with a higher likelihood of engaging in PA and a lower likelihood of engaging in SB. Conclusion Timing of menarche in girls and spermarche in boys could be a marker for PA and SB among Korean adolescents. To promote PA and discourage SB among Korean adolescents, school-based, grade-specific interventions can be tailored by the absence or presence of menarche/spermarche.

Keywords
Korea Youth Risk Behavior Web-based Survey, Korean adolescents, physical activity, pubertal timing, sedentary behavior

Age of thelarche and menarche in contemporary US females: a cross-sectional analysis.
Cabrera, S. M., Bright, G. M., Frane, J. W., Blethen, S. L., & Lee, P. A.
Journal of Pediatric Endocrinology & Metabolism, January, 2014

Abstract
AIM: A recent secular trend towards earlier thelarche has been suggested. The aim of this study is to examine normative ages of thelarche and menarche in contemporary US females. METHODS: Trained physicians documented Tanner breast stage by observation in a cross-sectional cohort. Age of menarche was self-reported. The subjects were healthy female children and adolescents. The mean age of thelarche was determined by probit analysis and the mean age of menarche was determined by using a normal time-to-event model. RESULTS: Mean age of thelarche was 9.7 years among 610 females aged 3.0-17.9 years (70% non-Hispanic Caucasian (NHC), 14% African-Americans, 7% Hispanic, 9%

Keywords
female, menarche

Prevalence, frequency, and associations of masturbation with partnered sexual behaviors among US adolescents.
Robbins, C. L., Schick, V., Reece, M., Herbenick, D., Sanders, S. A., Dodge, B., & Fortenberry, J. D.
Archives of Pediatrics & Adolescent Medicine, May, 2011

Abstract
Objective To assess masturbation prevalence, frequency, and associations with partnered sexual behaviors. Design Cross-sectional survey. Setting The United States of America. Participants Nationally representative samples of adolescents aged 14 to 17 years. Main Outcome Measures Solo masturbation, partnered sexual behaviors, and condom use. Results Across age groups, more males (73.8%) reported masturbation than females (48.1%). Among males, masturbation occurrence increased with age: at age 14 years, 62.6% of males reported at least 1 prior occurrence, whereas 80% of 17-year-old males reported ever having masturbated. Recent masturbation also increased with age in males: 67.6% of 17-year-olds reported masturbation in the past month, compared with 42.9% of 14-year-olds. In females, prior masturbation increased with age (58% at age 17 years compared with 43.3% at age 14 years), but recent masturbation did not. Masturbation was associated with numerous partnered sexual behaviors in both males and females. In males, masturbation was associated with condom use, but in females it was not. Conclusions Sexual development is a dynamic process during adolescence, and masturbation is an enduring component of sexuality. Fundamental differences appear to exist between male and female sexual expression. Health care providers should recognize that many teens masturbate and discuss masturbation with patients because masturbation is integral to normal sexual development. Masturbation carries no risk of pregnancy or sexually transmitted infections and may have benefits to sexual and emotional health.1,2 While one major study of male and female college students found no association, positive or negative, between a history of masturbation during early adolescence and sexual satisfaction during young adulthood,3 other studies have shown positive relationships. Among women, masturbation in childhood and adolescence has been associated with positive sexual experiences later in life4 and a healthy self-image.5 In another study of adolescent females aged 16 to 18, those with negative or indifferent views about masturbation reported negative first sexual experiences compared with those who held positive views of masturbation.6 Masturbation is thought to be a common behavior. In studies of older adolescents and adults, masturbation is nearly universal among males and reported by a majority of females.7-11 In an Australian study, 58% of males and 42% of females aged 15 to 18 years reported at least 1 lifetime episode of masturbation.2 Masturbation onset was found to occur by age 13 years in 53% of males and 25% of females in another retrospective study.12 Also, in a recent national sample of sexual behaviors in the United States (from which data for the current study were obtained), masturbation was more common than any partnered sexual behavior among 14- to 17-year-old adolescents.13 Despite its apparent widespread prevalence, masturbation is a highly stigmatized

Keywords
masturbation

Patterns of Gender Development.
Martin, C. L., & Ruble, D. N.
Annual Review of Psychology, January, 2010

Abstract
A comprehensive theory of gender development must describe and explain long-term developmental patterning and changes and how gender is experienced in the short term. This review considers multiple views on gender patterning, illustrated with contemporary research. First, because developmental research involves understanding normative patterns of change with age, several theoretically important topics illustrate gender development: how children come to recognize gender distinctions and understand stereotypes, and the emergence of prejudice and sexism. Second, developmental researchers study the stability of individual differences over time, which elucidates developmental processes. We review stability in two domains—sex segregation and activities/interests. Finally, a new approach advances understanding of developmental patterns, based on dynamic systems theory. Dynamic systems theory is a metatheoretical framework for studying stability and change, which developed from the study of complex and nonlinear systems in physics and mathematics. Some major features and examples show how dynamic approaches have been and could be applied in studying gender development.

Keywords
gender typing, stereotypes, dynamic systems, sex segregation, timescales

Pornography, sexual socialization, and satisfaction among young men.
Štulhofer, A., Buško, V. & Landripet, I.
Archives of Sexual Behavior, Feburary, 2010

Abstract
In spite of a growing presence of pornography in contemporary life, little is known about its potential effects on young people's sexual socialization and sexual satisfaction. In this article, we present a theoretical model of the effects of sexually explicit materials (SEM) mediated by sexual scripting and moderated by the type of SEM used. An on-line survey dataset that included 650 young Croatian men aged 18-25 years was used to explore empirically the model. Descriptive findings pointed to significant differences between mainstream and paraphilic SEM users in frequency of SEM use at the age of 14, current SEM use, frequency of masturbation, sexual boredom, acceptance of sex myths, and sexual compulsiveness. In testing the model, a novel instrument was used, the Sexual Scripts Overlap Scale, designed to measure the influence of SEM on sexual socialization. Structural equation analyses suggested that negative effects of early exposure to SEM on young men's sexual satisfaction, albeit small, could be stronger than positive effects. Both positive and negative effects-the latter being expressed through suppression of intimacy-were observed only among users of paraphilic SEM. No effect of early exposure to SEM was found among the mainstream SEM users. To counterbalance moral panic but also glamorization of pornography, sex education programs should incorporate contents that would increase media literacy and assist young people in critical interpretation of pornographic imagery.

Keywords
pornography, sexual socialization, satisfaction

Gender, ethnicity, and the developmental timing of first sexual and romantic experiences.
Regan, P. C., Durvasula, R., Howell, L., Ureño, O., & Rea, M.
Social Behavior and Personality: An International Journal, November, 2004

Abstract
One of the most important tasks faced by adolescents and young adults is the formation of romantic relationships. Little is known, however, about the developmental timing of early relational experiences. This study investigated the age at which an ethnically diverse sample of young adults (N = 683) experienced their very first date, love, serious relationship, kiss, and act of intercourse. Most had experienced each event by the end of high school, with first dates and kisses occurring at earlier ages than falling in love or intercourse. Gender and ethnic differences were found. For example, young men began dating at earlier ages than did young women. Asian American participants were less sexually and romantically experienced, and had their very first sexual experiences at an older age, than African American, Latino/Hispanic, and Caucasian/non-Hispanic White participants. Interestingly, there were no differences in first romantic love experience. Almost all men and women within each ethnic group had fallen in love at least once, typically around age 17; this suggests that romantic love is a common human life event and that it first occurs during the developmental period spanning late adolescence and early adulthood.

Keywords
ethnicity, gender, romantic experiences, sexual experiences