Here is another study by the same group who did the 1991 Pediatrics study.
Am J Dis Child 1989 Jan;143(1):86-90
Reported sexual behaviors and self-esteem among young adolescents.
Orr DP, Wilbrandt ML, Brack CJ, Rauch SP, Ingersoll GM.
Department of Pediatrics, Indiana University School of Medicine, Indianapolis.
Six hundred seventy-seven adolescents in grades 7 through 9 of a blue-collar, midwestern junior high school responded to a survey of sexual behavior and self-esteem. The focus of this study was on the relationship between sexual experience and self-esteem. Fifty-five percent of the students reported having had at least one coital experience; 7% reported having intercourse about once a week. The proportion of sexually experienced adolescents increased with age; 28% of 12-year-olds, 52.7% of 13-year-olds, 60.1% of 14-year-olds, 73.6% of 15-year-olds, and 90% of 16-year-olds reported having intercourse on at least one occasion. More boys of all ages were sexually active than girls. Six percent of students had had, or were suspicious of having had, a sexually transmitted disease; 7.8% were involved in a pregnancy. The average of the self-esteem scores for girls was significantly lower than the average for boys. There was an interaction effect between gender and coital history for self-esteem. Girls who reported having had intercourse had lower self-esteem scores than those who did not. On the other hand, self-esteem of sexually experienced and inexperienced boys did not differ, nor did self-esteem of virginal boys and girls. Boys and girls with a history of sexually transmitted diseases had lower self-esteem than all others. Pregnancy, on the other hand, did not seem to affect self-esteem of the sexually experienced adolescents. This cross-sectional study does not permit determination of whether the lower average self-esteem among certain girls was antecedent to or a consequence of sexual experience.
As you can see, it can't be decided what effects came first. It's also interesting to note that apart from the kids who had a history of STD:s, only the nonvirginal girls have lower self esteem, not the boys. So either girls with low self esteem have earlier sex, or girls get lower self esteem by having sex, whereas boys do not.
An interesting note: According to the same kind of study (Youth Risk Behaviour Study), in a sample of over 4000 9-12 grade girls, 1 of 5 had experienced date violence, and controlling for other factors, there was a correlation to substance abuse and other risk behaviour. In this context, it should also be noted that in a poll (I have the ref at work, I can post it later if you wish), 50% of US boys report that they would rape a girl if they were sure no legal consequences would follow. This factor should also be taken into account when we ask ourselves why there is a correlation between certain behaviours.
JAMA 2001 Aug 1;286(5):572-9
Dating violence against adolescent girls and associated substance use, unhealthy weight control, sexual risk behavior, pregnancy, and suicidality.
Silverman JG, Raj A, Mucci LA, Hathaway JE.
Division of Public Health Practice, Harvard School of Public Health, 1552 Tremont St, Boston, MA 02120, USA.
CONTEXT: Intimate partner violence against women is a major public health concern. Research among adults has shown that younger age is a consistent risk factor for experiencing and perpetrating intimate partner violence. However, no representative epidemiologic studies of lifetime prevalence of dating violence among adolescents have been conducted. OBJECTIVE: To assess lifetime prevalence of physical and sexual violence from dating partners among adolescent girls and associations of these forms of violence with specific health risks. DESIGN, SETTING, AND PARTICIPANTS: Female 9th through 12th-grade students who participated in the 1997 and 1999 Massachusetts Youth Risk Behavior Surveys (n = 1977 and 2186, respectively). MAIN OUTCOME MEASURES: Lifetime prevalence rates of physical and sexual dating violence and whether such violence is independently associated with substance use, unhealthy weight control, sexual risk behavior, pregnancy, and suicidality. RESULTS: Approximately 1 in 5 female students (20.2% in 1997 and 18.0% in 1999) reported being physically and/or sexually abused by a dating partner. After controlling for the effects of potentially confounding demographics and risk behaviors, data from both surveys indicate that physical and sexual dating violence against adolescent girls is associated with increased risk of substance use (eg, cocaine use for 1997, odds ratio [OR], 4.7; 95% confidence interval [CI], 2.3-9.6; for 1999, OR, 3.4; 95% CI, 1.7-6.7), unhealthy weight control behaviors (eg, use of laxatives and/or vomiting [for 1997, OR, 3.2; 95% CI, 1.8-5.5; for 1999, OR, 3.7; 95% CI, 2.2-6.5]), sexual risk behaviors (eg, first intercourse before age 15 years [for 1997, OR, 8.2; 95% CI, 5.1-13.4; for 1999, OR, 2.4; 95% CI, 1.4-4.2]), pregnancy (for 1997, OR, 6.3; 95% CI, 3.4-11.7; for 1999, OR, 3.9; 95% CI, 1.9-7.8), and suicidality (eg, attempted suicide [for 1997, OR, 7.6; 95% CI, 4.7-12.3; for 1999, OR, 8.6; 95% CI, 5.2-14.4]). CONCLUSION: Dating violence is extremely prevalent among this population, and adolescent girls who report a history of experiencing dating violence are more likely to exhibit other serious health risk behaviors.
And another study from Pediatrics:
Pediatrics 1993 Jul;92(1):13-9
Early initiation of sex and its lack of association with risk behaviors among adolescent African-Americans.
Stanton B, Romer D, Ricardo I, Black M, Feigelman S, Galbraith J.
Department of Pediatrics, University of Maryland Medical School, Baltimore 21201.
OBJECTIVE. High rates of adolescent homicide, pregnancy, substance abuse, and sexually transmitted diseases underscore the importance of interventions designed to reduce problem behaviors. However, the definition of "problem" behavior and the association with other activities may change between youth cultures. Therefore, greater attention to defining the "problem" behaviors to be targeted will permit more effective utilization of primary vs secondary intervention strategies and identification of high-risk individuals. DESIGN. Two studies of African-American adolescents regarding sexual intercourse, school truancy, substance abuse, and drug trafficking are presented. The first study involved 57 youths (10 to 14 years of age) from a pediatric primary health center and gathered data through pile-sorting. The second study of 300 youths (9 to 15 years of age) from six public housing sites used a questionnaire administered by a "talking" computer. Both studies assessed different self-reported behaviors, feelings about engaging in specific behaviors, and perceptions of friends' behaviors. RESULTS. While 40% of subjects reported having had sex, substantially smaller proportions reported school truancy (14%), illicit drug use (2% to 6%), or drug trafficking (6%). Analyses of reported behaviors, feelings, and perceived peer norms revealed that sex was consistently depicted as forming a different domain from other problem behaviors. CONCLUSIONS. Interventions that rely on primary prevention strategies for sexual intercourse and that identify sexually active youths as at risk for problem behaviors may not be appropriate for African-American adolescents growing up in resource-depleted urban areas.
So the correlation doesn't hold for this Afro-American sample. Why is that? Black Americans are the most christian people in the world according to polls. Still, this youth sample from a black community does not show a correlation between early sex and problem behaviours.
Since Orr et al's results were not replicable in the Afro-American population, what about other populations? Other countries and cultures? Unfortunately I haven't time to go deeper in to this right now, but with a quick search I could not find any studies from other countries that demostrated the same correlations as Ingersoll's. A South Korean study reported a correlation between drug use, not having two parents, living away from parents and living in Seoul (biggest city). So far, we don't know whether the correlations Orr reports only are representative for the white US population, or if it can be generalised further.
This was actually an interesting area, if anyone wants to use the free Medline (Pubmed) to look for studies, the address is:
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed
If you find something interesting, you can always click "related article" in the right corner and you'll get back abstracts of articles concerning the same area. You only get abstracs, for access to full articles one must pay.