Age at Sexual Debut Through a Life Course Lens: A Sex-Stratified Analysis

Objectives: Sexual debut is an important milestone in sexual development and is often used as an indicator of adolescent sexual health. Early sexual debut, defined as first penile-vaginal intercourse between the ages of 11 and 14, has been linked to a range of psychosocial, behavioral, and reproductive health outcomes and reflects broader inequities in access to safe, consensual, and informed sexual experiences. Guided by life course theory, this cross-sectional study examined how individual, familial, and socioeconomic factors shape age at sexual debut and assessed whether these associations differ by sex. Methods: Data from the 2011–2013, 2013–2015, 2015–2017, and 2017–2019 waves of the National Survey of Family Growth (NSFG) were pooled, yielding an analytic sample of 32,670 participants aged 15–49 years. Age at sexual debut was categorized as early (11–14 years), normative (15–17 years), or later (≥18 years; reference). Descriptive statistics and polytomous logistic regression models estimated associations between exposures and age at sexual debut, adjusting for all covariates. Interaction terms evaluated sex differences. Results: Being male, living in a childhood home without two parents, having a mother with a low education, having a mother who gave birth at a young age, and the absence of a mother figure were risk factors for early sexual debut. Interaction analyses revealed that Black and Hispanic males had elevated odds of early sexual debut, while these racial/ethnic associations were not observed among females. Conclusion: Findings demonstrate how timing of events, linked lives, and socioeconomic context, core pillars of life course theory, contribute to unequal pathways toward sexual debut. Although some determinants are not modifiable, factors such as parental monitoring, family communication, and access to comprehensive sexuality education represent actionable opportunities to support equitable sexual development and improve sexual health outcomes.