How old are young people when they start having sex? Unravelling the applicability of Cox proportional hazards regression

Abstract

Purpose How old are young people when they start having sex? Although this question is important for educators and policymakers, its answer can easily mislead due to methodology that does not take into account age-censoring and generational trends. This study investigated whether 1-year birth-year cohorts can be jointly modeled by Cox proportional hazards regression to estimate sexual debut ages and to investigate age trends for different sexual behaviors. Method We used pooled data from three Dutch periodic population-based surveys, for which 33,377 participants, born between 1980 and 2004, completed an online questionnaire. Results Cox proportional hazards regression is appropriate if hazard changes over birth years appear proportionally similar among ages. The Dutch data shows such hazard changes for petting, oral sex, and sexual intercourse, but not for masturbation, French kissing, or manual sex. For sexual intercourse, the Cox model estimates can be interpreted as an approximate linear increase of 1 month in the median sexual debut age per birth-year cohort, resulting in an estimated debut age of 18.17 years in the current (2020) generation of Dutch adolescents. Conclusion If the assumptions are met, we recommend using the Cox regression modeling approach to estimate how old young people are when they start having sex, since this method yields precise and current debut ages by pooling information across birth-year cohorts without arbitrarily combining them in multiple-year groups. The age of first intercourse is increasing, so continuous sexuality education throughout high school is advisable, in addition to early sexuality education.

(Dis)continuation of the oral contraceptive pill: A focus group approach in the Netherlands

“…Finally, social influences, through communication with peers and the general practitioner, influence decision-making. This is also reported by Melo et al [ 17 ], stressing the importance of peers and healthcare providers in different stages of the decision-making process and reflected in the systematic review of Ti et al [ 23 ] in which is shown that the social context affect contraceptive values and preferences. Moreover, the importance of online information seeking in the context of social influences became clear in this study.…”

“…In 2017, 94% of young women and 92% of young men (aged 12–25 years) reported to have use any contraceptive during their first intercourse. The median age of OCP users in the Netherlands is 25–29 years [ 23 ]. In 2011, the Dutch College of General Practitioners adopted a new standard for contraception, which emphasized the importance of providing comprehensive information about a wide range of contraceptive methods to enable individuals to make informed decisions based on their personal preferences.…”

Changes in sexually transmitted infections-related sexual risk-taking among young Croatian adults: a 2005-2021 three-wave population-based study

“…Ubiquitous social media use among young people (45,46) could be a partial replace-tABLe 4. Binary logistic regressions with sexual partners in the past year, condom use at first sexual intercourse, consistent condom use in the past year, and concurrent sexual relationships as outcomes, study wave as predictor, and basic socio-demographics as controls, by gender* † sexual partners (past year) (0 = 0 and 1; 1 = 2 or more) ment or even a barrier for real-life sexual interactions given that online social networking provides new forms of sexual expression (47), increases insecurity regarding physical appearance and sexual performance (48,49), supplies entertainment that may compete with sexual activity (15) (such as video streaming services and online sexual contents) (50), and impedes the development of face-to-face communication skills (51,52). Another possible explanation is delayed transition to adulthood (50,53,54), which involves postponed partnered cohabitation and prolonged co-residence with parents.…”

“…Decreased sexual activity, delayed coital debut, and a lower number of sexual partners are attributed to several recent developments. Ubiquitous social media use among young people ( 45 , 46 ) could be a partial replacement or even a barrier for real-life sexual interactions given that online social networking provides new forms of sexual expression ( 47 ), increases insecurity regarding physical appearance and sexual performance ( 48 , 49 ), supplies entertainment that may compete with sexual activity ( 15 ) (such as video streaming services and online sexual contents) ( 50 ), and impedes the development of face-to-face communication skills ( 51 , 52 ). Another possible explanation is delayed transition to adulthood ( 50 , 53 , 54 ), which involves postponed partnered cohabitation and prolonged co-residence with parents.…”