Contextualizing pubertal development: The combination of sexual partners' age and girls' pubertal development confers risk for externalizing but not internalizing symptoms among girls in therapeutic day schools

Objective: Early pubertal development is associated with negative health and mental health outcomes. Research on the influence of puberty on mental health underscores a need to examine the interplay between puberty and exposure to environmental risk. This study investigates a more rarely studied aspect of girls’ environments – romantic relationships with boyfriends. Specifically, this study examined sexual partner age and the timing of girls’ pubertal development in relation to externalizing and internalizing symptoms among female students attending therapeutic day schools in the United States, a population at elevated risk for negative mental health outcomes. Methods: A total of 121 13 to 19-year-old adolescent girls (Mean age = 15.4; SD = 1.5) reported on the relative age of their past 3 sexual partners, their age of pubertal onset, and mental health challenges via clinical assessments of externalizing and internalizing symptoms. Results: Forty-three percent of participants qualified for at least one mental health diagnosis. Earlier pubertal onset predicted greater internalizing symptoms, and this effect did not depend on the age of girls’ sexual partners. However, early-developing girls who also reported having a sexual partner more than 2 years older than them were at increased risk for externalizing symptoms. Conclusions: Findings underscore that sexual relationships are an important risk factor for early-developing girls already at risk for mental health problems. Early developing girls with older partners may experience stronger social pressure to stay in relationships that expose them to partner violence and delinquency-related pressure, which combine with interpersonal stress to predict externalizing symptoms.