摘要：Objectives. We examined the prospective association between negative life events and time to initiation of sexual intercourse and the influence of family structure and family income on this association. Methods. We followed up a randomly selected sample (n = 649) of ethnically diverse parents and their children aged 12 to 17 years over a 5-year period. We conducted Cox proportional hazards regression analysis to examine the relation between negative life events and time to initiation of sexual intercourse. Family structure and family income were assessed as confounders. Results. Negative life events were significant predictors of time to initiation of sexual intercourse in adolescents. After controlling for demographic variables, youths reporting 1 negative life event had a hazard of initiation of sexual intercourse 1.40 times greater and youths reporting 2 or more negative life events had a hazard of initiation of sexual intercourse 1.61 times greater compared with youths reporting no negative life events. Family structure and family income were not significant confounders of the relation between initiation of sexual intercourse and negative life events. Conclusions. Interventions to prevent initiation of sexual intercourse should focus on youths with recent negative life events, regardless of family income and structure. Negative life events are changes in the social or physical environment that disrupt life routines. 1 Negative life events such as the death of a family member, divorce, or moving to a new school or city have the potential to substantially affect an adolescent’s life because the behaviors adopted to cope with them may continue well past the actual event. 2–4 Negative life events have been significantly associated with health risk behaviors and psychiatric symptoms in children and adolescents, particularly depression and anxiety, 5–8 smoking, 9–11 and alcohol abuse. 12 To date, no published studies have examined the association between negative life events and initiation of sexual intercourse in adolescents. The prevention of adolescent sexual risk behaviors is important because of the health, social, and economic costs of sexually transmitted diseases and adolescent pregnancy. 13–15 Adolescent birthrates have declined steadily since the 1950s, 16 yet rates in the United States remain higher than in most other developed countries. 17 Almost half (47%) of high-school students have had sexual intercourse, with rates ranging from 33% of 9th graders to 63% of 12th graders. 18 Reductions in birthrates have occurred primarily in older adolescents, whereas rates for youths aged 10 to 14 years have remained largely unchanged. 16 Early initiation of sexual intercourse (by ages 13–14 years) can increase the risk of pregnancy and sexually transmitted diseases. 19 One fourth of sexually active adolescent females are living with a sexually transmitted disease. 20 Adolescents who initiate sexual intercourse earlier are also at greater risk for unwanted intercourse, lower rates of contraception use, and greater numbers of sexual partners. 21 Adolescent births have significant social and economic consequences. Adolescent mothers are more likely to drop out of high school and live in poverty. 22,23 Moreover, children of adolescent parents are more likely to drop out of high school, become incarcerated, have more behavioral and medical issues, and give birth as an adolescent themselves. 22 Thus, sexual activity in adolescents continues to be an important public health issue. Sexual risk behaviors and adolescent pregnancy have been retrospectively associated with cumulative traumatic experiences, such as physical abuse and emotional neglect, throughout childhood and adolescence in the Adverse Childhood Experiences study 24–27 ; however, no prospective studies have tested the association between more commonly experienced negative life events and initiation of sexual intercourse in adolescents. Family income and family structure are associated with negative life events and initiation of sexual intercourse. 7,8,28–39 Family income and family structure can influence the type of negative life events that youths are exposed to, the social resources they have available to manage them, and the behaviors youths adopt to cope with them. 40,41 One in 4 adolescents lives in a household with just 1 parent. 28,29 Adolescents in 1-parent families report more negative life events than do adolescents in 2-parent families, 30–32 in part because a change in family structure, such as divorce, can trigger a series of negative life events, such as moving to another neighborhood, changing schools, or experiencing a significant decrease in income. 7,33 Adolescents living in 1-parent families are also more likely to report earlier initiation of sexual intercourse compared with those living in 2-parent families. 34–37 Adolescents living in lower-income families experience more negative life events than do those living in higher-income families. 8,31,38 In general, for both 1- and 2-parent families, as family socioeconomic status increases, the likelihood of adolescents initiating sexual intercourse decreases. 34,39 Although the relation between negative life events, family structure, and family income has been established, how family structure and income influence the association between negative life events and initiation of sexual intercourse in adolescents has not been explored. Family structure and income may be confounding variables and as such may distort the true relation between negative life events and initiation of sexual intercourse, even though they are not in the causal path. 42 If family structure and family income are confounders, not accounting for them can lead to an underestimation or overestimation of the effects of negative life events on initiation of sexual intercourse. 43 The purpose of this study was to examine the prospective association between negative life events and initiation of sexual intercourse. We also investigated the potential roles of family structure and family income as confounding variables.
