Abstract
PURPOSE: To examine how age of onset of sexual intercourse is associated with past-year and lifetime sexually transmitted infections (STIs) and depression in young adulthood. METHODS: We examined how occurrence of a lifetime and past-year STI, lifetime diagnosis of depression, and past-week depressive symptoms differed as a function of age of onset of sexual intercourse using data from the National Longitudinal Study of Adolescent to Adult Health (Add Health; N = 8,938 individuals). Time-varying effect models were used to examine how age of onset, measured as continuous age, was associated with these outcomes in young adulthood, with all analyses stratified to examine gender differences. RESULTS: Individuals who engaged in first intercourse before age 16 reported higher than average rates of all outcomes studied; for example, an estimated 35% of women and 12% of men who initiated at age 14 years reported a lifetime STI, compared with about 5% of those who initiated at age 24 years. Timing of first intercourse past the mid-twenties was associated with lower than average rates of STIs and lifetime depression diagnoses but was associated with a somewhat higher level of past-year depressive symptoms. Patterns were similar by gender, although there was little difference in men's depression diagnoses by age of onset. CONCLUSIONS: Results suggest that sexual intercourse before age 16 years may be associated with higher rates of STIs and depression. Findings provide support for comprehensive programs that both promote delay of first intercourse and provide safe sex and psychological support for those who initiate early.