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Prospective Association Between Negative Life Events and Initiation of Sexual Intercourse: The Influence of Family Structure and Family Income Marshall K. Cheney, PhD, Roy F. Oman, PhD, Sara K. Vesely, PhD, Cheryl B. Aspy, PhD, Eleni L. Tolma, PhD, and Robert John, PhD

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

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. (Am J Public Health. 2015;105:598–604. doi:10.2105/ AJPH.2014.302311)

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 study24---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

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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

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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.

METHODS Adolescent---parent pairs (n = 1111) living in ethnically and economically diverse neighborhoods in Oklahoma County, Oklahoma, were surveyed annually for 5 waves of data collection. Household eligibility criteria for participation in the study included at least 1 adolescent between ages 12 and 17 years with at least 1 parent or guardian living in the household whose primary language was either English or Spanish. The questionnaire was administered in the participating family’s home with computer-assisted interviewing methods. The parent and adolescent were interviewed at the same time in separate parts of the house. The questionnaires took about 1 hour to complete and covered a range of adolescent health risk behaviors and the influence of personal, family, and neighborhood factors that promote or protect against the adoption of health risk behaviors.44 We collected baseline data from August 2003 to December 2004. We followed up the adolescent---parent pairs for the next 4 years, completing interviews each year. Data collection concluded in December 2008. The retention rate across all 5 waves (i.e., valid completed youth interview

for all 5 waves) was 89% (986/1111). We examined data from waves 2 through 5.

Measures Initiation of sexual intercourse. We assessed initiation of sexual intercourse with the question, “Have you ever had sexual intercourse (‘done it,’ ‘had sex,’ ‘made love,’ ‘gone all the way’)?” This question has established validity and is commonly used in research.45,46 The first year youths responded “yes” to this question, they were considered to have initiated sexual intercourse sometime in the past year and therefore were censored at later time points. Family structure and family income (confounding variables). Family structure was measured in the adolescent interview via the question, “How many parents do you live with?” Youths could respond “two,” “one,” or “do not live with a parent/guardian/supervising adult.” Family structure was categorized as 2-parent, 1-parent, or inconsistent households, which were defined as youths residing in both 1- and 2-parent households over the 5 data collection periods or being independent from parents before age 18 years. Family income was represented as per-capita income. Parents were asked, “What was your total family income in [past year] before taxes? Please include your total family income, including your income and the income of your husband/partner (if living with you in [past year]) and your children. Please include income from all sources including jobs, welfare, disability, unemployment, retirement, child support, interest, dividends, and support from family members for the year [past year].” The midpoint of the income range selected by the parent was divided by the parent response to “Thinking back to [past year], how many people lived on this income?” Age. Youths who reported no initiation of sexual intercourse at wave 1 were grouped into 3 age categories based on their ages at wave 2: 13 to 14, 15 to 16, and 17 to 19 years. Negative Life Events Scale. The Negative Life Events Scale is a 14-item scale adapted from life events scales used with adults and college students.47---49 We modified the scale to reflect events appropriate for adolescents. We measured negative life events with the following question: Next I am going to read some things that may have happened to you in the past year. These

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things, or life events, may bring about changes in the lives of those who experience them. As I read them to you, first tell me if the life event happened to you DURING THE PAST YEAR, answer “yes” or “no”; if you answer “yes,” please tell me whether it was a “good” or “bad” thing; and then tell me how much the event affected your life (“no effect,” “some effect,” “moderate effect,” or a “great effect.”).

Youths also were allowed to volunteer life events that were not included as one of the original events. Only events rated as “bad” by the youths were counted as negative events. Negative life events were grouped into categories of none, 1, and 2 or more events. Life event data were collected in waves 2 through 5 of the study. Consistent with other studies of negative life events, the impact rating (perceived intensity of the experience) did not add any additional information in prior analyses and is not reported here.50,51

Analysis The overall study included 1111 youths. The goal of this analysis was to use negative life events to predict initiation of sexual intercourse at the subsequent wave; therefore, only the 649 youths who reported never having had sexual intercourse at wave 2 were included in the analysis. Youths were excluded from the analysis if they were missing demographic information or did not respond to the family structure, initiation of sexual intercourse, or life event questions. Youths also were censored after their 20th birthday or reported that they got married or began to live with someone in a romantic relationship. We conducted Cox proportional hazards regression analysis to examine the relation between time-varying negative life events and time to initiation of sexual intercourse over the next 3 years of the study. Single negative life events were examined separately. We examined total negative life events after adjusting for family structure and time-varying per-capita family income as well as participant race/ ethnicity, gender, and age. We examined all 2-way interactions. We then assessed confounding between time to initiation of sexual intercourse and negative life events and family structure, per-capita family income, gender, and age (separately) in the Cox proportional hazards regression. Because of the large

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number of tied survival times, we used the exact method to produce accurate estimates because we believe that the events did not all occur at the same time but as a result of imprecise measurement.52 Confounding was characterized by a change of more than 15% in the parameter estimate (hazard ratio = e parameter estimate ) between negative life events and time to initiation of sexual intercourse when per-capita family income or family structure was added to the model. 43,53,54 The analysis was performed with SAS 9.2 (SAS Institute, Cary, NC). An a of 0.05 was used throughout the study.

RESULTS Of the 649 youths who reported no initiation of sexual intercourse at wave 2, 22% reported initiation of sexual intercourse at wave 3; 18% of those who had no initiation of sexual intercourse at wave 3 reported initiation of sexual intercourse at wave 4; 14% of those who had no initiation of sexual intercourse at wave 4 reported initiation of sexual intercourse at wave 5; and 46% reported no initiation of sexual intercourse during the follow-up period. In wave 2, participants ranged in age from 13 to 19 years (mean age = 14.9 years; SD = 1.5 years), 53% were female, 56% were ethnic minorities, and 62% consistently lived in 2-parent families. Approximately 25% of the youths lived in families with a per-capita income less than $5000, and 27% of the youths lived in families with a per-capita income of $16 500 or more (Table 1).

Individual Negative Life Events and Initiation of Sexual Intercourse The prevalence of each negative life event at waves 2 to 4 is shown in Table 2. Across waves, the negative life events reported most often were death of a family member, a change in family finances, more conflict at home, more problems in school, a major personal illness, and ending a romantic relationship. The category “other events not mentioned” included a wide range of responses such as a sick family member, friend or sibling moving, friend or sibling in trouble, family disruption, and being threatened by others. Table 2 also shows the association of negative single life events across study waves with

time to initiation of sexual intercourse. The hazard ratio represents the unadjusted risk of initiation of sexual intercourse for youths who experienced the negative life event compared with youths who did not. Three negative life events experienced over the past 12 months were individually associated with time to initiation of sexual intercourse. Significant hazard ratios ranged from 1.32 for problem in school to 1.77 for parent separation or divorce over the past 12 months.

Prospective Association Between Negative Life Events and Initiation of Sexual Intercourse We used Cox proportional hazards regression to prospectively test the association between time-varying negative life events and time to initiation of sexual intercourse in years (Table 3). The time-varying negative life events were lagged (i.e., a negative life event at wave 2 was used to predict initiation of sexual intercourse at wave 3 [1 year later], negative life events at wave 3 were used to predict initiation of sexual intercourse at wave 4 [1 year later], and negative life events at wave 4 were used to predict initiation of sexual intercourse at wave 5 [1 year later]). Models 1 through 6 showed that the risk of initiation of sexual intercourse (shown as the hazard ratio) over the next 3 waves of the study increased as the number of life events increased from 1 event to 2 or more events. In the fully adjusted model (model 6), negative life events, age, race/ethnicity (nonHispanic Black and Hispanic vs non-Hispanic White), and per-capita income ($5000---$9999 vs ‡$16 500) were significantly associated with time to initiation of sexual intercourse. The hazard of initiation of sexual intercourse for youths who reported 1 negative life event was 1.40 times the hazard of those who reported no negative life events after we controlled for the demographic variables. Youths who reported 2 or more negative life events had a hazard of initiation of sexual intercourse 1.61 times greater than did youths reporting no events after we controlled for the demographic variables. Black youths had 1.67 times the hazard of initiation of sexual intercourse than did White youths, and in the fully controlled model, Hispanic youths had a hazard of initiation of sexual intercourse 1.37 times greater than did White youths.

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TABLE 1—Descriptive Statistics for Study Participants (n = 649): Oklahoma County, Oklahoma, 2003– 2008 Characteristic

No. (%)

Gender Female

345 (53)

Male Age at wave 2

304 (47)

13–14 y

309 (48)

15–16 y

236 (36)

17–19 y

104 (16)

Ethnicity Non-Hispanic White

286 (44)

Non-Hispanic Black

115 (18)

Hispanic Non-Hispanic other

181 (28) 67 (10)

Family structure through the study 2-parent family

401 (62)

1-parent family

128 (20)

Mixed/independent

120 (18)

Per-capita family income at wave 2, $ 0–4 999

146 (23)

5 000–9 999

153 (24)

10 000–16 499

160 (25)

‡ 16 500

183 (29)

Did not initiate sexual

301 (46)

intercourse at wave 3, 4, or 5 Initiated sexual intercourse at wave 3, 4, or 5 Wave 3

140 (22)

Wave 4

119 (18)

Wave 5

89 (14)

Not unexpectedly, there was a significant association between time to initiation of sexual intercourse and age at each step in the regression model (Table 3); however, age was not a confounder because it did not change the relation between negative life events and time to initiation of sexual intercourse when it was entered into the model. The hazard of initiation of sexual intercourse was 1.32 times greater for youths who were 15 to 16 years old at wave 2 (reaching ages 18---19 years by wave 5) compared with youths aged 13 to 14 years at wave 2. Youths who were 17 to 18 years old had a hazard ratio of 1.52 as compared with youths aged 13 to 14 years at

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TABLE 2—Individual Negative Life Events and Their Association With Initiation of Sexual Intercourse in Adolescents: Oklahoma County, Oklahoma, 2003–2008 Experienced Negative Life Event Wave 2 (n = 645), No. (%)

Wave 3 (n = 642), No. (%)

Wave 4 (n = 630), No. (%)

Time to Initiation of Sexual Intercourse, HR (95% CI)

Major personal illness

93 (14)

87 (14)

93 (15)

1.09 (0.80, 1.47)

Change of school

17 (3)

16 (2)

17 (3)

1.47 (0.78, 2.78)

Problem in school

124 (19)

107 (17)

125 (20)

1.32* (1.01, 1.73)

Change residence within the same city

7 (1)

7 (1)

7 (1)

1.64 (0.67, 4.01)

Move to a different city

6 (1)

8 (1)

6 (1)

1.79 (0.73, 4.36)

Break up or get “dumped”

88 (14)

93 (14)

88 (14)

1.34* (1.01, 1.79)

Get married or begin living with someone Parent separation or divorce

0 (0) 20 (3)

0 (0) 22 (3)

0 (0) 20 (3)

NA 1.77* (1.09, 2.85)

Negative Events Reported

Make a new friend

9 (1)

1.10 (0.35, 3.44)

More conflict at home

102 (16)

124 (19)

102 (16)

1.14 (0.87, 1.50)

Death of family or friend

220 (34)

217 (34)

222 (35)

1.24 (0.99, 1.54)

Change in family finance

83 (13)

88 (14)

84 (13)

0.93 (0.67, 1.27)

Parent gained in spouse/partner

12 (2)

14 (2)

12 (2)

1.45 (0.77, 2.73)

Other event not mentioned

25 (4)

15 (2)

25 (4)

0.95 (0.51, 1.79)

Total negative life events reported 0

8 (1)

3 (< 1)

222 (34)

220 (34)

198 (31)

1

207 (32)

190 (30)

203 (32)

‡2

216 (33)

232 (36)

229 (36)

Note. CI = confidence interval; HR = hazard ratio; NA = not applicable. *P < .05.

wave 2. Age was independently associated with time to initiation of sexual intercourse. No significant interactions occurred between negative life events and other study variables.

Role of Family Structure and Per-Capita Income as Confounding Variables The Cox proportional hazards regression (Table 3) shows the hazard for the prospective association of negative life events and time to initiation of sexual intercourse. The parameter estimate did not change by more than 15% when family structure and family income were each added to the model. Thus, when the definition of confounding was applied, neither family structure nor family income confounded the relation between negative life events and time to initiation of sexual intercourse.

DISCUSSION Negative life events were significant predictors of initiation of sexual intercourse in

adolescents. This is consistent with retrospective studies of adverse life events and sexual intercourse, linking severe or traumatic events in childhood to later high-risk sexual behaviors.24---27 This study was the first to show that lower-intensity negative events increased the risk of initiation of sexual intercourse in adolescents. Even 1 negative life event puts youths at risk for initiation of sexual intercourse. Problems in school, breaking up or getting “dumped,” and parent separation or divorce significantly increased the risk for initiation of sexual intercourse. Moreover, the results suggested that multiple negative life events substantially increased the likelihood of initiation of sexual intercourse in comparison with youths with 1 negative life event. This cumulative effect is consistent with other studies of adolescents that involved negative life events and other health risk behaviors.10---12,55 The graded prospective association of negative life events and initiation of sexual intercourse supports the

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accumulation of risk model, which predicts that adolescents who are exposed to more negative life events have an increased risk of adopting unhealthy behaviors.2---4 The model proposes that it is the buildup of negative life events over time, more than the characteristics of individual events or their severity, that increases the risk of unhealthy behaviors. Consistent with the model, youths in this study had an increasing risk of initiation of sexual intercourse the following year for each additional negative life event reported. This study also investigated the role of family structure and family income as confounding variables in the relation between negative life events and initiation of sexual intercourse. These variables represent potential social resources or contextual advantages available to adolescents and have been associated with decreased risk of a variety of potentially health-harming behaviors.56,57 Per-capita family income and family structure did not act as confounders in the association between negative life events and initiation of sexual intercourse (i.e., they did not mask or distort the true relation between negative life events and initiation of sexual intercourse). In addition, the interactions between negative life events and both family structure and family income were not significant. This indicates that the social advantages of higher income and a 2-parent family perhaps did not provide adequate resources for youths to draw on in resolving stress caused by relatively common negative life events. Consistent with previous literature, nonHispanic Black and Hispanic youths had a greater risk of initiation of sexual intercourse after we controlled for other study variables.18 This could indicate additional sources of social disadvantage such as racial discrimination or differing social norms. The interaction of negative life events with ethnicity was not significant, indicating that although risk of initiation of sexual intercourse was greater for Black and Hispanic youths (Table 3), they were not affected any more or less than White youths were by negative life events. This is consistent with the finding that the interaction between negative life events and family income was not significant because ethnicity is often associated with income. One recommendation for future research is to focus on increasing the understanding of

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TABLE 3—Hazard Ratios for the Prospective Association of Negative Life Events and Time to First Intercourse: Oklahoma County, Oklahoma, 2003–2008 Model 1

Model 2

Model 3

Model 4

Model 5

Model 6

Negative eventsa 0 (Ref)

1.00

1.00

1.00

1.00

1.00

1.00

1

1.40* (1.06, 1.84)

1.43* (1.08, 1.88)

1.39* (1.05, 1.83)

1.40* (1.06, 1.85)

1.38* (1.05, 1.83)

1.40* (1.06, 1.85)

‡2

1.59* (1.22, 2.08)

1.65* (1.26, 2.15)

1.65* (1.26, 2.16)

1.64* (1.25, 2.15)

1.61* (1.23, 2.11)

1.61* (1.23, 2.11)

Age, y 13–14 (Ref)

1.00

1.00

1.00

1.00

1.00

15–16

1.32* (1.05, 1.65)

1.28* (1.02, 1.62)

1.31* (1.04, 1.65)

1.32* (1.04, 1.66)

1.32* (1.05, 1.68)

17–19

1.56* (1.09, 2.24)

1.54* (1.07, 2.22)

1.55* (1.07, 2.24)

1.55* (1.08, 2.23)

1.52* (1.05, 2.20)

Ethnicity Non-Hispanic White (Ref)

1.00

Non-Hispanic Black

1.74* (1.31, 2.03)

Hispanic

1.00

1.00

1.76* (1.31, 2.36)

1.00

1.63* (1.21, 2.18)

1.67* (1.24, 2.25)

1.28 (0.99, 1.67)

1.33 (0.99, 1.80)

1.27 (0.98, 1.65)

1.37* (1.01, 1.86)

0.80 (0.53, 1.21)

0.80 (0.53, 1.21)

0.81 (0.53, 1.22)

0.81 (0.54, 1.22)

Female (Ref)

1.00

1.00

1.00

1.00

Male

1.13 (0.91, 1.40)

1.13 (0.91, 1.40)

1.13 (0.91, 1.40)

1.13 (0.91, 1.41)

2-parent (Ref)

1.00

1.00

1-parent

1.29 (0.98, 1.69)

1.32 (1.00, 1.75)

Mixed/independent

1.29 (0.97, 1.70)

1.28 (0.97, 1.70)

Non-Hispanic other Gender

Family structure

Per-capita family income,a $ 0–4 999 5 000–9 999

1.00 (0.70, 1.42)

0.91 (0.64, 1.31)

0.74 (0.54, 1.01)

0.72* (0.52, 0.99)

10 000–16 499

1.04 (0.78, 1.38)

1.04 (0.78, 1.38)

‡ 16 500 (Ref)

1.00

1.00

a

Life events and per-capita income were time-varying and lagged. *P < .05.

how the social environment or social norms influence perceptions of life events and the behaviors, positive or negative, that youths adopt in response to that event.40,41 Are we underestimating the association of negative life events with unhealthy behavior because we are assessing risk 1 behavior at a time? Or are youths influenced by their social environments to adopt one behavior rather than another?4 Future studies also should examine the relation between negative life events and initiation of sexual intercourse for different age groups of adolescents. Although the interaction between negative life events and age group was not significant in this study (not shown), the trend was for those in the youngest age group to report more negative life events and to have a stronger association between negative life events and initiation of sexual intercourse.

Implications for Research and Practice Negative life events have the potential to significantly affect an adolescent’s life because the behaviors adopted to cope with them may have consequences that continue past the event itself. These findings can be used to help researchers and practitioners design interventions to help youths cope with the stress from negative life events in a more constructive manner. A simple life events checklist can be useful in identifying youths at increased risk for initiation of sexual intercourse and other health risk behaviors. Public health practitioners, educators, and counselors should be aware of the effect of negative life events on initiation of sexual intercourse. Parents, teachers, health care professionals, and other adults who interact with youths may discount the effect of

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common negative experiences youths are likely to encounter in adolescence and their cumulative influence on adopting health risk behaviors. Paying more attention to the smaller events and questioning how youths cope with stress and the skills they have to manage the stress from even 1 event or increasing stress from cumulative events could help youths cope with stress more productively. Screenings during health care provider office visits and school counselor visits can alert practitioners to life stressors youths are experiencing and to an increased risk for engaging in unhealthy behaviors. Practitioners also can educate parents about the increased risk for engaging in unhealthy behaviors in response to negative life events. These findings also show that social advantage, measured through family structure and

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family income, does not influence the relation between negative life events and risk for sexual intercourse in adolescents. Furthermore, the nonsignificant interaction should prompt practitioners to direct prevention efforts to all youths with a recent history of negative life events, not just those in disadvantaged communities.

Limitations This study had limitations, including sample size in later waves and reporting of initiation of sexual intercourse. By studying incidence and limiting age to younger than 20 years, the sample size was reduced by a quarter (22%) from wave 1 to wave 2, which was the first year negative life events were measured, and by 41% from wave 2 to wave 5, which limited statistical power to detect associations in later waves. Time from the negative life event to initiation of sexual intercourse was also variable because of how we assessed negative life events (within the past 12 months) and time to initiation of sexual intercourse (within the next wave). This may have created a window of up to 2 years between the experience of the negative life event and initiation of sexual intercourse. Two of the life events were parent divorce or separation and remarriage. These are similar to the proposed confounder, family structure. Although these are similar, it is important to remember that the life events were included in the analysis only if they were rated as negative by youths. Thus, family structure may have changed multiple times over the course of the study but was relevant as a negative event only if youths felt that it was negative. These are common negative events for youths, so they were left in the scale to capture their influence on initiation of sexual intercourse when youths rated them negatively. Although unlikely because of survey procedures, youths report of initiation of sexual intercourse may have been influenced by social acceptability, and some may not have admitted to initiation of sexual intercourse even though they responded to the question privately. Time to initiation of sexual intercourse also may have been influenced by other variables not measured in the current study, such as characteristics of the sexual network.

Conclusions Negative life events were significant predictors of initiation of sexual intercourse in

adolescents. The costs of early initiation of sexual intercourse and risky sexual behaviors are high, both to individual adolescents and to society. Negative life events may make youths more vulnerable to engaging in health risk behaviors compared with those without recent negative life events. Interventions to prevent initiation of sexual intercourse should focus on adolescents reporting negative life events, regardless of family income and family structure. j

About the Authors Marshall K. Cheney is with the Department of Health and Exercise Science, University of Oklahoma, Norman. Roy F. Oman, Eleni L. Tolma, and Robert John are with the Department of Health Promotion Sciences, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City. Sara K. Vesely is with the Department of Biostatistics and Epidemiology, College of Public Health, University of Oklahoma Health Sciences Center, Oklahoma City. Cheryl B. Aspy is with the Department of Family and Preventive Medicine, University of Oklahoma Health Sciences Center, Oklahoma City. Correspondence should be sent to Marshall K. Cheney, PhD, Department of Health and Exercise Science, University of Oklahoma, 1401 Asp Ave, Norman, OK 73019 (e-mail: [email protected]). Reprints can be ordered at http://www.ajph.org by clicking the “Reprints” link. This article was accepted September 5, 2014.

Contributors M. K. Cheney conceptualized the study, conducted the data analysis and interpretation of results, and drafted the article. R. F. Oman assisted with conceptualization of the study and interpretation of results and contributed to development of the article. S. K. Vesely conceptualized the data analysis and oversaw data analysis, interpretation of results, and development of the article. C. B. Aspy contributed to development of the article and data collection. E. L. Tolma and R. John assisted with conceptualization of the study and development of the article.

Acknowledgments The Youth Asset Study was supported under a cooperative agreement from the Centers for Disease Control and Prevention (grant 5 U01 DP000132) and the Inasmuch Foundation. Note. The contents of this article are solely the responsibility of the authors and do not necessarily represent the official views of the funding agencies.

Human Participant Protection This project underwent and received full review and approval by the University of Oklahoma Health Sciences Center internal review board.

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