Abstract

Background

To describe the characteristics of a population with high-risk sexual behaviours and associations between sexual intercourse, high-risk sexual behaviours and socio-demographic characteristics among Chinese urban adolescents.

Methods

In 2005, 109 754 students in grades 10–12 and 33 653 college students were anonymously surveyed using a Chinese Youth Risk Behaviour Survey. Demographic variables and indicators of forced sex, condom use and unintended pregnancy were analysed with multiple logistic regressions.

Results

Of students surveyed, median age was 17.6 (range 14–24 years) and 76 233 were female (53.2%); 4.8% of high school students reported had experienced sexual intercourse; of these, 32.8% reported had forced sex; 11.3% of college students reported had experienced sexual intercourse and of these, the prevalence of forced sex, condom use and unintended pregnancy were 23.5, 49.7 and 24.2%, respectively. School type and socioeconomic status were found to be independently associated with sexual intercourse and forced sex for high school students. For college students, educational level, school type, family structure, maternal education and socioeconomic status were independently associated with high-risk sexual behaviours.

Conclusion

This study highlights the association between high-risk sexual behaviours and school type and socioeconomic status. These results strongly suggest the importance of providing sex education in high schools and lower socioeconomic areas.

Introduction

In China, young people aged 10–24 accounted for 25% of the total population and 33% of the population urbanized in 2001,1 which was a large population that had been ignored in the field of reproductive health for long time. Although still a very low proportion of students had experienced sexual intercourse, especially for the high school students in China, the prevalence of sexual intercourse among adolescents had increased from not more than 1% in 1981 to 7% in 2004.2 There is evidence that this population are ill prepared for sexual intercourse.3–7 High-risk sexual behaviours are usually defined as behaviours involving unsafe sex with outcomes of unintended pregnancy and STIs, and many studies also showed that depression, suicidal ideation and suicide attempts have been linked to adolescent sexual activity, especially that associated with early sexual intercourse and sexual abuse,8–10 thus we focused our attention on unsafe sex, unintended pregnancy and forced sex.

In order to find out the prevalence and epidemic trend of health-risk behaviours among adolescents, a Chinese Youth Risk Behaviour Survey (CYRBS) was conducted first in this century in 2005, and we were able to have the opportunity to analyse the associations between high-risk sexual behaviours and socio-demographic characteristics. Although some studies had described the situation of sexual behaviours in Chinese adolescents, most of them used local data or a specific population, such as CYRBS in one city or province, or a clinic-based population, and little literature had examined the prevalence of sexual intercourse among this population in China from nationwide data. There was also little literature that had determined the associations between sexual intercourse, high-risk sexual behaviours and socio-demographic characteristics. In this study, we hypothesized that there were differences of sexual intercourse and high-risk sexual behaviours among adolescents living in different family structures, adolescents with parents who had higher educational background might have less high-risk sexual behaviours, adolescents who lived in developed socioeconomic areas would have more high-risk sexual behaviours and adolescents who studied in different school types might have different performance on sexual intercourse. The most worthwhile point is that China's high school system mainly includes key high schools (like Wellesley College in America, or St Paul's School in the UK), ordinary high schools (like comprehensive school) and vocational school, and the main differences among these three kinds of schools are the academic record of students.11 Ordinarily, the key school have students with outstanding academic record, the ordinary school have moderate academic record and the students in vocational schools often show poor performance. We would like to know if there was any difference in key schools, ordinary schools or vocational schools for high school students on high-risk sexual behaviours?

Methods

Sampling

This study was an initial analysis of data from the 2005 CYRBS, which was lead by professor J.CY., among urban adolescents in 18 provinces in China.12 The survey was designed to describe six categories of priority health-risk behaviours that contribute to the leading causes of death, disability and social problems in China. The survey used a three-stage cluster sample design to obtain a nationally representative sample of students in grades 7–12 and college students in 18 provinces (Fig. 1). At the first sampling stage, three cities or districts, highly developed, middle-developed and developing cities or districts of each province were sampled according to their socioeconomic level. At the second sampling stage, 863 schools were selected with probability proportional to school enrolment size. The third stage of sampling consisted of randomly selecting one or two intact classes from grades 7–12 or from freshman to senior class at each chosen school. All students in selected classes were eligible to participate in the survey. Information was obtained through anonymous self-administered questionnaires that assess behaviours related to unhealthy diet-related behaviours, physical inactivity, unintentional injuries and violence, substance use, net addiction and sexual behaviours that lead to unintended pregnancy and sexually transmitted diseases (this part was only for grades 10–12 and college students to answer), some socio-demographic characteristics, such as sex, grade, parental educational attainment, family structure were also obtained from the questionnaire, but the information about school type and socioeconomic status of residence was obtained from sampling. The national CYRBS was reviewed and approved by an Institutional Review Board.

Fig. 1

Nationally representative sample of students in grades 7–12 and college students in 18 provinces.

Fig. 1

Nationally representative sample of students in grades 7–12 and college students in 18 provinces.

Participants

For the part of sexual behaviours that lead to unintended pregnancy and sexually transmitted diseases, only 109 754 grade 10–12 students from 447 high schools and 33 653 college students from 84 colleges participated in this part as well as health-risk behaviour areas. Of these, median age was 17.6 (range 14–24 years) and 76 233 were female (53.2%).

The response rate of lifetime experience of sex behaviours among all students was 97.4%. The overall response rates of high-risk behaviours were 98.2% among high school students and 88.4% among college students, respectively.

Analysis

SPSS Statistical Software Package 10.0 for windows was used to perform all data analysis in the study. The overall analytic goal was to describe the sexual intercourse, high-risk sexual behaviours and associations with socio-demographic factors, and to examine the range of socio-demographic factors that were independently associated with sexual intercourse and high-risk sexual behaviours by testing them in a multivariate model (for further information see Supplementary material on the web).

Results

Descriptive and univariate analysis among high school students

In 18 provinces, 4.8% of grade 10–12 students reported had had sexual intercourse, of these, 32.8% reported had ever had forced sex. The prevalence of having had sexual intercourse was higher among male than female students (χ2 = 1345.2, P < 0.001) (Table 1); higher among vocational school students than key school and ordinary school students (6.9 versus 3.5 and 4.2%, χ2 = 498.6, P < 0.001); lowest among students who lived with both parents (χ2 = 277.1, P < 0.001); greatest among those students with mothers of junior college or more education for boys (χ2 = 19.6, P < 0.001) (Table 1); lower among students who lived in developing cities or districts than students who lived in highly developed or middle-developed cities or districts (4.3 versus 5.1 and 5.0%, χ2 = 29.2, P < 0.001) and increased with age (χ2linear-by-linear = 744.9, P < 0.001). The prevalence of having had forced sex was higher among female than male students (χ2 = 62.2, P < 0.001) (Table 1) and higher among key school students than vocational school and ordinary school students (36.9 versus 30.5 and 32.8%, χ2 = 16.0, P < 0.001); greatest among those students with mothers of junior college or more education for boys (χ2 = 27.2, P < 0.001) (Table 1); higher among students who lived in developing cities or districts than students who lived in the developed or middle-developed cities or districts (37.4 versus 31.2 and 31.0%, χ2 = 17.8, P < 0.001) and decreased with age (χ2linear-by-linear = 41.9, P < 0.001).

Table 1

Percentage of high school students who had sexual intercourse and forced sex, by sex and socio-demographic characteristics

 Sexual intercourse
 
Forced sexual intercoursea
 
 Female (n = 57 278)
 
Male (n = 50 468)
 
Female (n = 1482)
 
Male (n = 3719)
 
 % 95% CI % 95% CI % 95% CI % 95% CI 
Age (years) 
 14 2.2 (5) 0.3–4.1 5.2 (7) 1.4–9.0 40.0 (2) −28.0–108.0 28.6 (2) −16.6–73.7 
 15 1.5* (91) 1.2–1.8 3.7 (153) 3.1–4.3 58.2* (53) 47.9–68.6 32.2 (49) 24.7–39.8 
 16 2.0* (348) 1.8–2.2 5.6 (775) 5.2–6.0 46.6* (162) 41.3–51.8 33.5 (259) 30.2–36.8 
 17 2.8* (542) 2.6–3.1 6.9 (1220) 6.6–7.3 38.6* (209) 34.5–42.8 31.0 (377) 28.4–33.6 
 ≥18 3.6* (497) 3.3–3.9 10.7 (1577) 10.2–11.3 36.2* (180) 32.0–40.5 26.2 (411) 24.0–28.3 
Educational level 
 Grade 10 2.2* (520) 2.0–2.3 6.6 (1370) 6.3–6.9 44.5* (231) 40.2–48.8 29.6 (404) 27.2–32.0 
 Grade 11 2.8* (555) 2.6–3.0 7.4 (1374) 7.0–7.7 39.8* (221) 35.7–43.9 31.0 (424) 28.5–33.4 
 Grade 12 3.1* (408) 2.8–3.4 8.9 (988) 8.4–9.5 37.8* (154) 33.0–42.5 27.4 (270) 24.7–30.2 
School type 
 Key school 1.9* (353) 1.7–2.1 5.1 (960) 4.8–5.4 45.3* (160) 40.1–50.5 33.9 (325) 30.9–36.9 
 Ordinary school 2.0* (361) 1.8–2.2 6.6 (1146) 6.3–7.0 46.0* (166) 40.8–51.2 28.6 (326) 26.0–31.2 
 Vocational school 3.8* (767) 3.5–4.0 11.4 (1623) 10.9–11.9 36.4* (279) 33.0–39.8 27.7 (447) 25.5–29.9 
Family structure 
 Both parents 2.3* (1114) 2.1–2.4 6.9 (2980) 6.6–7.1 41.0* (456) 38.1–43.9 29.4 (874) 27.8–31.0 
 Single parent 3.9* (173) 3.3–4.4 10.3 (406) 9.4–11.3 40.5* (70) 33.1–47.9 26.7 (108) 22.3–31.0 
 One biological parent and one step parent 6.7* (70) 5.2–8.3 13.3 (79) 10.6–16.1 35.7# (25) 24.2–47.2 19.5 (15) 10.4–28.5 
 Grandparents 3.7* (45) 2.6–4.8 9.0 (95) 7.3–10.7 40.0 (18) 25.1–54.9 34.0 (32) 24.3–43.8 
 Other 6.8* (55) 5.1–8.6 12.1 (116) 10.0–14.2 45.5 (25) 31.9–59.0 41.7 (48) 32.6–50.9 
Maternal educational attainment 
 Junior high school or less 2.7* (732) 2.5–2.9 7.3 (1719) 7.0–7.6 44.1* (322) 40.4–47.7 29.9 (513) 27.7–32.1 
 Senior high school 2.4* (550) 2.2–2.6 7.1 (1386) 6.7–7.4 35.5* (195) 31.4–39.5 25.7 (355) 23.4–28.1 
 Junior college or more 2.7* (192) 2.3–3.1 8.7 (605) 8.0–9.3 43.8 (84) 36.7–50.8 37.3 (225) 33.4–41.2 
Paternal educational attainment 
 Junior high school or less 2.8* (591) 2.6–3.0 7.3 (1342) 7.0–7.7 45.2* (267) 41.2–49.2 29.3 (391) 26.8–31.7 
 Senior high school 2.4* (613) 2.3–2.6 7.1 (1547) 6.8–7.5 35.6* (218) 31.8–39.4 27.7 (428) 25.5–30.0 
 Junior college or more 2.5* (273) 2.2–2.8 8.0 (813) 7.5–8.5 44.0* (120) 38.0–50.0 33.1 (268) 29.8–36.3 
Socioeconomic status 
 Lives in developed cities/districts 3.0* (619) 2.7–3.2 7.7 (1342) 7.3–8.1 35.0# (216) 31.2–38.7 29.4 (392) 27.0–31.9 
 Lives in middle-developed cities/districts 2.6* (467) 2.3–2.8 7.7 (1333) 7.3–8.1 42.0* (196) 37.5–46.5 27.2 (362) 24.8–29.6 
 Lives in developing cities/districts 2.2* (368) 2.0–2.4 6.8 (1002) 6.4–7.2 49.5* (182) 44.3–54.6 32.9 (329) 30.0–35.8 
Total 2.6* (1483) 2.5–2.7 7.4 (3732) 7.2–7.6 40.9 (606) 38.4–43.4 29.5 (1098) 28.1–31.0 
 Sexual intercourse
 
Forced sexual intercoursea
 
 Female (n = 57 278)
 
Male (n = 50 468)
 
Female (n = 1482)
 
Male (n = 3719)
 
 % 95% CI % 95% CI % 95% CI % 95% CI 
Age (years) 
 14 2.2 (5) 0.3–4.1 5.2 (7) 1.4–9.0 40.0 (2) −28.0–108.0 28.6 (2) −16.6–73.7 
 15 1.5* (91) 1.2–1.8 3.7 (153) 3.1–4.3 58.2* (53) 47.9–68.6 32.2 (49) 24.7–39.8 
 16 2.0* (348) 1.8–2.2 5.6 (775) 5.2–6.0 46.6* (162) 41.3–51.8 33.5 (259) 30.2–36.8 
 17 2.8* (542) 2.6–3.1 6.9 (1220) 6.6–7.3 38.6* (209) 34.5–42.8 31.0 (377) 28.4–33.6 
 ≥18 3.6* (497) 3.3–3.9 10.7 (1577) 10.2–11.3 36.2* (180) 32.0–40.5 26.2 (411) 24.0–28.3 
Educational level 
 Grade 10 2.2* (520) 2.0–2.3 6.6 (1370) 6.3–6.9 44.5* (231) 40.2–48.8 29.6 (404) 27.2–32.0 
 Grade 11 2.8* (555) 2.6–3.0 7.4 (1374) 7.0–7.7 39.8* (221) 35.7–43.9 31.0 (424) 28.5–33.4 
 Grade 12 3.1* (408) 2.8–3.4 8.9 (988) 8.4–9.5 37.8* (154) 33.0–42.5 27.4 (270) 24.7–30.2 
School type 
 Key school 1.9* (353) 1.7–2.1 5.1 (960) 4.8–5.4 45.3* (160) 40.1–50.5 33.9 (325) 30.9–36.9 
 Ordinary school 2.0* (361) 1.8–2.2 6.6 (1146) 6.3–7.0 46.0* (166) 40.8–51.2 28.6 (326) 26.0–31.2 
 Vocational school 3.8* (767) 3.5–4.0 11.4 (1623) 10.9–11.9 36.4* (279) 33.0–39.8 27.7 (447) 25.5–29.9 
Family structure 
 Both parents 2.3* (1114) 2.1–2.4 6.9 (2980) 6.6–7.1 41.0* (456) 38.1–43.9 29.4 (874) 27.8–31.0 
 Single parent 3.9* (173) 3.3–4.4 10.3 (406) 9.4–11.3 40.5* (70) 33.1–47.9 26.7 (108) 22.3–31.0 
 One biological parent and one step parent 6.7* (70) 5.2–8.3 13.3 (79) 10.6–16.1 35.7# (25) 24.2–47.2 19.5 (15) 10.4–28.5 
 Grandparents 3.7* (45) 2.6–4.8 9.0 (95) 7.3–10.7 40.0 (18) 25.1–54.9 34.0 (32) 24.3–43.8 
 Other 6.8* (55) 5.1–8.6 12.1 (116) 10.0–14.2 45.5 (25) 31.9–59.0 41.7 (48) 32.6–50.9 
Maternal educational attainment 
 Junior high school or less 2.7* (732) 2.5–2.9 7.3 (1719) 7.0–7.6 44.1* (322) 40.4–47.7 29.9 (513) 27.7–32.1 
 Senior high school 2.4* (550) 2.2–2.6 7.1 (1386) 6.7–7.4 35.5* (195) 31.4–39.5 25.7 (355) 23.4–28.1 
 Junior college or more 2.7* (192) 2.3–3.1 8.7 (605) 8.0–9.3 43.8 (84) 36.7–50.8 37.3 (225) 33.4–41.2 
Paternal educational attainment 
 Junior high school or less 2.8* (591) 2.6–3.0 7.3 (1342) 7.0–7.7 45.2* (267) 41.2–49.2 29.3 (391) 26.8–31.7 
 Senior high school 2.4* (613) 2.3–2.6 7.1 (1547) 6.8–7.5 35.6* (218) 31.8–39.4 27.7 (428) 25.5–30.0 
 Junior college or more 2.5* (273) 2.2–2.8 8.0 (813) 7.5–8.5 44.0* (120) 38.0–50.0 33.1 (268) 29.8–36.3 
Socioeconomic status 
 Lives in developed cities/districts 3.0* (619) 2.7–3.2 7.7 (1342) 7.3–8.1 35.0# (216) 31.2–38.7 29.4 (392) 27.0–31.9 
 Lives in middle-developed cities/districts 2.6* (467) 2.3–2.8 7.7 (1333) 7.3–8.1 42.0* (196) 37.5–46.5 27.2 (362) 24.8–29.6 
 Lives in developing cities/districts 2.2* (368) 2.0–2.4 6.8 (1002) 6.4–7.2 49.5* (182) 44.3–54.6 32.9 (329) 30.0–35.8 
Total 2.6* (1483) 2.5–2.7 7.4 (3732) 7.2–7.6 40.9 (606) 38.4–43.4 29.5 (1098) 28.1–31.0 

aAmong students who had had sexual intercourse.

*,#Gender difference significant at P < 0.01, P < 0.05.

Descriptive and univariate analysis among college students

About 11.3% of college students reported had ever had sexual intercourse, and of these, the prevalence of forced sex, condom use and unintended pregnancy were 23.5, 49.7 and 24.2%, respectively. The prevalence of having had forced sex was higher among female than male students (χ2 = 63.4, P < 0.001) (Table 2); higher among undergraduate college students than junior college students (24.6 versus 20.2%, χ2=6.8, P < 0.001); lowest among students who lived with both parents than other students for boys (χ2 = 15.0, P < 0.001) and decreased with age (χ2linear-by-linear = 42.1, P < 0.001). The prevalence of condom use was lowest among students who lived in developing cities or districts (χ2 = 12.8, P < 0.001) and increased with age (χ2linear-by-linear = 16.5, P < 0.001). The prevalence of unintended pregnancies was higher among female than male students (χ2 = 7.5, P < 0.001) and greatest among those students with mothers of junior college or more education for boys (χ2 = 8.4, P < 0.001) (Table 2).

Table 2

Percentage of college students who had sexual intercourse and high-risk sexual behaviours, by sex and socio-demographic characteristics

 Sexual intercourse
 
Forced sexual intercoursea
 
Condom usea
 
Had been pregnant or gotten someone else pregnanta
 
 Female (n = 17125)
 
Male (n = 14739)
 
Female (n = 1124)
 
Male (n = 2371)
 
Female (n = 1138)
 
Male (n = 2416)
 
Female (n = 1113)
 
Male (n = 2331)
 
 % 95% CI % 95% CI % 95% CI % 95% CI % 95% CI % 95% CI % 95% CI % 95% CI 
Age (years) 
 ≤18 3.5* (82) 2.7–4.2 7.8 (92) 6.3–9.3 49.4# (39) 38.1–60.6 33.0 (30) 23.1–42.8 45.1 (41) 34.6–55.5 34.8 (31) 24.7–44.9 30.7 (23) 20.0–41.4 32.2 (29) 22.4–42.1 
 19 4.9* (200) 4.3–5.6 12.1 (287) 10.8–13.4 37.6* (71) 30.6–44.5 26.2 (72) 21.0–31.4 45.3 (81) 37.9–52.6 43.5 (114) 37.5–50.0 29.8 (57) 23.3–36.4 23.2 (62) 18.1–28.3 
 20 6.3* (310) 5.6–7.0 15.4 (644) 14.3–16.5 29.0* (87) 23.8–34.2 20.1 (125) 17.0–23.3 50.9 (164) 45.4–56.4 48.5 (298) 44.5–52.4 22.1 (64) 17.3–26.9 25.1 (151) 21.6–28.6 
 21 9.5* (297) 8.5–10.5 17.9 (575) 16.5–19.2 26.6* (77) 21.4–31.7 18.1 (101) 14.9–21.3 54.0 (150) 48.1–59.9 49.1 (283) 45.0–53.2 29.3* (84) 24.0–34.6 19.1 (105) 15.8–22.4 
 ≥22 10.6* (257) 9.4–11.9 22.0 (757) 20.6–23.4 31.8* (80) 26.0–37.5 15.3 (113) 12.7–17.8 57.5 (142) 51.3–63.7 51.4 (411) 47.9–54.9 27.2 (69) 21.7–32.7 22.4 (166) 19.4–25.4 
Educational level 
 Freshmen 4.3* (254) 3.8–4.8 11.5 (525) 10.5–12.4 41.6* (96) 35.2–48.0 23.2 (115) 19.5–27.0 44.1 (109) 37.9–50.4 44.8 (226) 40.4–49.1 31.6# (77) 25.7–37.4 23.7 (120) 20.0–27.4 
 Sophomores 6.8* (416) 6.2–7.4 16.0 (872) 15.1–17.0 32.4* (131) 27.8–36.9 21.2 (178) 18.4–23.9 47.2 (195) 42.4–52.1 44.7 (372) 41.3–48.1 28.1 (112) 23.7–32.6 27.6 (225) 24.5–30.7 
 Juniors 9.7* (380) 8.8–10.7 21.8 (775) 20.5–23.2 28.7* (108) 24.1–33.3 16.4 (126) 13.7–19.0 56.7 (207) 51.6–61.8 52.7 (418) 49.2–56.2 25.1* (91) 20.7–29.6 17.9 (134) 15.1–20.6 
 Seniors 9.8* (113) 8.1–11.5 23.1 (268) 20.7–25.6 20.5 (23) 12.9–28.1 17.4 (46) 12.8–22.0 69.0# (78) 60.4–77.7 55.9 (160) 50.2–61.7 20.2 (22) 12.5–27.8 20.7 (54) 15.7–25.6 
School type 
 Junior college 6.0* (277) 5.3–6.7 17.1 (560) 15.8–18.4 29.2 (80) 23.8–34.6 15.8 (88) 12.7–18.8 47.9 (127) 41.9–54.0 48.0 (238) 43.6–52.4 25.2 (66) 19.9–30.5 20.8 (105) 17.2–24.3 
 Undergraduate college 7.1* (886) 6.6–7.5 16.4 (1880) 15.7–17.1 32.7 (278) 29.6–35.9 20.8 (377) 18.9–22.7 52.9 (462) 49.6–56.2 48.9 (938) 46.6–51.1 27.7 (236) 24.7–20.8 23.5 (428) 21.5–25.4 
Family structure 
 Both parents 6.3* (965) 5.9–6.7 16.1 (2092) 15.5–16.7 29.9* (279) 27.0–32.9 18.7 (379) 17.0–20.4 50.8 (480) 47.7–54.0 48.2 (988) 46.1–50.4 25.8# (238) 23.0–28.6 22.4 (447) 20.5–24.2 
 Single parent 8.7* (96) 7.0–10.4 19.0 (187) 16.5–21.4 45.2* (42) 34.9–55.5 23.0 (42) 16.8–29.1 56.9 (58) 47.1–66.6 50.2 (103) 43.3–57.2 30.1 (28) 20.6–39.6 24.6 (45) 18.3–30.9 
 One biological parent and one step parent 18.0 (37) 12.7–23.3 21.4 (28) 14.3–28.5 28.6 (10) 12.8–44.3 25.0 (7) 7.9–42.1 63.6 (21) 46.3–81.0 47.1 (16) 29.4–64.7 20.0 (7) 6.1–33.9 24.0 (6) 6.0–42.0 
 Grandparents 8.5* (18) 4.7–12.3 20.5 (39) 14.7–26.3 27.8 (5) 4.9–50.7 26.3 (10) 11.7–41.0 50.0 (8) 22.5–77.5 50.0 (17) 32.3–67.7 17.7 (3) –2.6–37.9 18.4 (7) 5.5–31.3 
 Other 18.2 (41) 13.1–23.3 24.4 (73) 19.5–29.3 47.5 (19) 31.3–63.7 35.2 (25) 23.8–46.6 55.3 (21) 38.7–71.8 51.4 (36) 39.4–63.4 57.5# (23) 41.5–73.5 37.7 (26) 26.0–49.4 
Maternal educational attainment 
 Junior high school or less 6.4* (590) 5.9–6.9 15.2 (1365) 14.4–15.9 33.1* (190) 29.2–37.0 20.1 (266) 18.0–22.3 49.7 (287) 45.6–53.7 47.0 (654) 44.4–49.6 27.0* (155) 23.3–30.6 21.5 (286) 19.3–23.7 
 Senior high school 6.5* (398) 5.9–7.2 17.5 (772) 16.3–18.6 27.7* (105) 23.2–32.2 19.0 (143) 16.2–21.9 54.1 (216) 49.2–59.1 50.6 (380) 47.0–54.2 25.5 (96) 21.1–30.0 22.7 (166) 19.6–25.7 
 Junior college or more 10.0* (170) 8.6–11.5 23.7 (297) 21.4–26.1 36.8* (61) 29.3–44.2 18.4 (54) 14.0–22.9 53.2 (83) 45.3–61.1 52.6 (140) 46.6–58.7 31.9 (50) 24.5–39.2 29.7 (78) 24.1–35.2 
Paternal educational attainment 
 Junior high school or less 6.7* (476) 6.1–7.3 15.6 (1021) 14.7–16.5 36.9* (171) 32.5–41.4 21.0 (207) 18.5–23.5 51.0 (229) 46.4–55.6 47.3 (486) 44.2–50.3 29.3# (136) 25.1–33.4 24.4 (242) 21.7–27.1 
 Senior high school 6.3* (427) 5.7–6.8 15.8 (890) 14.9–16.8 26.2* (107) 21.9–30.5 19.0 (164) 16.4–21.6 49.1 (212) 44.3–53.8 48.9 (438) 45.7–52.2 26.0# (106) 21.7–30.3 20.0 (171) 17.3–22.7 
 Junior college or more 8.3* (259) 7.3–9.3 20.7 (522) 19.2–22.3 31.8* (80) 26.0–37.5 17.9 (92) 14.5–21.2 57.6 (147) 51.5–63.8 50.9 (248) 46.5–55.4 25.1 (60) 19.6–30.6 24.8 (118) 20.9–28.7 
Socioeconomic status 
 Lives in developed cities/districts 7.4* (456) 6.7–8.0 16.8 (1033) 15.8–17.7 30.8* (140) 26.6–35.1 18.8 (194) 16.4–21.2 50.4 (207) 45.5–55.2 48.3 (459) 45.1–51.5 29.0# (120) 24.6–33.4 22.8 (212) 20.1–25.5 
 Lives in middle-developed cities/districts 7.4* (387) 6.7–8.1 17.4 (691) 16.2–18.5 30.7* (113) 26.0–35.4 20.6 (135) 17.5–23.8 54.6 (215) 49.6–59.5 53.4 (380) 49.8–57.1 26.1 (99) 21.6–30.5 22.5 (154) 19.3–25.6 
 Lives in developing cities/districts 5.9* (287) 5.2–6.5 15.3 (567) 14.2–16.5 35.7* (96) 29.9–41.5 20.0 (107) 16.6–23.4 51.5# (151) 45.8–57.3 43.3 (259) 39.3–47.3 28.0 (80) 22.7–33.2 24.4 (138) 20.9–28.0 
Total 6.7* (1163) 6.3–7.0 16.2 (2440) 15.6–16.8 31.9* (358) 29.1–34.6 19.6 (465) 18.0–21.2 51.8 (589) 48.9–54.7 48.7 (1176) 46.7–50.7 27.1* (302) 24.5–29.8 22.9 (533) 21.2–24.6 
 Sexual intercourse
 
Forced sexual intercoursea
 
Condom usea
 
Had been pregnant or gotten someone else pregnanta
 
 Female (n = 17125)
 
Male (n = 14739)
 
Female (n = 1124)
 
Male (n = 2371)
 
Female (n = 1138)
 
Male (n = 2416)
 
Female (n = 1113)
 
Male (n = 2331)
 
 % 95% CI % 95% CI % 95% CI % 95% CI % 95% CI % 95% CI % 95% CI % 95% CI 
Age (years) 
 ≤18 3.5* (82) 2.7–4.2 7.8 (92) 6.3–9.3 49.4# (39) 38.1–60.6 33.0 (30) 23.1–42.8 45.1 (41) 34.6–55.5 34.8 (31) 24.7–44.9 30.7 (23) 20.0–41.4 32.2 (29) 22.4–42.1 
 19 4.9* (200) 4.3–5.6 12.1 (287) 10.8–13.4 37.6* (71) 30.6–44.5 26.2 (72) 21.0–31.4 45.3 (81) 37.9–52.6 43.5 (114) 37.5–50.0 29.8 (57) 23.3–36.4 23.2 (62) 18.1–28.3 
 20 6.3* (310) 5.6–7.0 15.4 (644) 14.3–16.5 29.0* (87) 23.8–34.2 20.1 (125) 17.0–23.3 50.9 (164) 45.4–56.4 48.5 (298) 44.5–52.4 22.1 (64) 17.3–26.9 25.1 (151) 21.6–28.6 
 21 9.5* (297) 8.5–10.5 17.9 (575) 16.5–19.2 26.6* (77) 21.4–31.7 18.1 (101) 14.9–21.3 54.0 (150) 48.1–59.9 49.1 (283) 45.0–53.2 29.3* (84) 24.0–34.6 19.1 (105) 15.8–22.4 
 ≥22 10.6* (257) 9.4–11.9 22.0 (757) 20.6–23.4 31.8* (80) 26.0–37.5 15.3 (113) 12.7–17.8 57.5 (142) 51.3–63.7 51.4 (411) 47.9–54.9 27.2 (69) 21.7–32.7 22.4 (166) 19.4–25.4 
Educational level 
 Freshmen 4.3* (254) 3.8–4.8 11.5 (525) 10.5–12.4 41.6* (96) 35.2–48.0 23.2 (115) 19.5–27.0 44.1 (109) 37.9–50.4 44.8 (226) 40.4–49.1 31.6# (77) 25.7–37.4 23.7 (120) 20.0–27.4 
 Sophomores 6.8* (416) 6.2–7.4 16.0 (872) 15.1–17.0 32.4* (131) 27.8–36.9 21.2 (178) 18.4–23.9 47.2 (195) 42.4–52.1 44.7 (372) 41.3–48.1 28.1 (112) 23.7–32.6 27.6 (225) 24.5–30.7 
 Juniors 9.7* (380) 8.8–10.7 21.8 (775) 20.5–23.2 28.7* (108) 24.1–33.3 16.4 (126) 13.7–19.0 56.7 (207) 51.6–61.8 52.7 (418) 49.2–56.2 25.1* (91) 20.7–29.6 17.9 (134) 15.1–20.6 
 Seniors 9.8* (113) 8.1–11.5 23.1 (268) 20.7–25.6 20.5 (23) 12.9–28.1 17.4 (46) 12.8–22.0 69.0# (78) 60.4–77.7 55.9 (160) 50.2–61.7 20.2 (22) 12.5–27.8 20.7 (54) 15.7–25.6 
School type 
 Junior college 6.0* (277) 5.3–6.7 17.1 (560) 15.8–18.4 29.2 (80) 23.8–34.6 15.8 (88) 12.7–18.8 47.9 (127) 41.9–54.0 48.0 (238) 43.6–52.4 25.2 (66) 19.9–30.5 20.8 (105) 17.2–24.3 
 Undergraduate college 7.1* (886) 6.6–7.5 16.4 (1880) 15.7–17.1 32.7 (278) 29.6–35.9 20.8 (377) 18.9–22.7 52.9 (462) 49.6–56.2 48.9 (938) 46.6–51.1 27.7 (236) 24.7–20.8 23.5 (428) 21.5–25.4 
Family structure 
 Both parents 6.3* (965) 5.9–6.7 16.1 (2092) 15.5–16.7 29.9* (279) 27.0–32.9 18.7 (379) 17.0–20.4 50.8 (480) 47.7–54.0 48.2 (988) 46.1–50.4 25.8# (238) 23.0–28.6 22.4 (447) 20.5–24.2 
 Single parent 8.7* (96) 7.0–10.4 19.0 (187) 16.5–21.4 45.2* (42) 34.9–55.5 23.0 (42) 16.8–29.1 56.9 (58) 47.1–66.6 50.2 (103) 43.3–57.2 30.1 (28) 20.6–39.6 24.6 (45) 18.3–30.9 
 One biological parent and one step parent 18.0 (37) 12.7–23.3 21.4 (28) 14.3–28.5 28.6 (10) 12.8–44.3 25.0 (7) 7.9–42.1 63.6 (21) 46.3–81.0 47.1 (16) 29.4–64.7 20.0 (7) 6.1–33.9 24.0 (6) 6.0–42.0 
 Grandparents 8.5* (18) 4.7–12.3 20.5 (39) 14.7–26.3 27.8 (5) 4.9–50.7 26.3 (10) 11.7–41.0 50.0 (8) 22.5–77.5 50.0 (17) 32.3–67.7 17.7 (3) –2.6–37.9 18.4 (7) 5.5–31.3 
 Other 18.2 (41) 13.1–23.3 24.4 (73) 19.5–29.3 47.5 (19) 31.3–63.7 35.2 (25) 23.8–46.6 55.3 (21) 38.7–71.8 51.4 (36) 39.4–63.4 57.5# (23) 41.5–73.5 37.7 (26) 26.0–49.4 
Maternal educational attainment 
 Junior high school or less 6.4* (590) 5.9–6.9 15.2 (1365) 14.4–15.9 33.1* (190) 29.2–37.0 20.1 (266) 18.0–22.3 49.7 (287) 45.6–53.7 47.0 (654) 44.4–49.6 27.0* (155) 23.3–30.6 21.5 (286) 19.3–23.7 
 Senior high school 6.5* (398) 5.9–7.2 17.5 (772) 16.3–18.6 27.7* (105) 23.2–32.2 19.0 (143) 16.2–21.9 54.1 (216) 49.2–59.1 50.6 (380) 47.0–54.2 25.5 (96) 21.1–30.0 22.7 (166) 19.6–25.7 
 Junior college or more 10.0* (170) 8.6–11.5 23.7 (297) 21.4–26.1 36.8* (61) 29.3–44.2 18.4 (54) 14.0–22.9 53.2 (83) 45.3–61.1 52.6 (140) 46.6–58.7 31.9 (50) 24.5–39.2 29.7 (78) 24.1–35.2 
Paternal educational attainment 
 Junior high school or less 6.7* (476) 6.1–7.3 15.6 (1021) 14.7–16.5 36.9* (171) 32.5–41.4 21.0 (207) 18.5–23.5 51.0 (229) 46.4–55.6 47.3 (486) 44.2–50.3 29.3# (136) 25.1–33.4 24.4 (242) 21.7–27.1 
 Senior high school 6.3* (427) 5.7–6.8 15.8 (890) 14.9–16.8 26.2* (107) 21.9–30.5 19.0 (164) 16.4–21.6 49.1 (212) 44.3–53.8 48.9 (438) 45.7–52.2 26.0# (106) 21.7–30.3 20.0 (171) 17.3–22.7 
 Junior college or more 8.3* (259) 7.3–9.3 20.7 (522) 19.2–22.3 31.8* (80) 26.0–37.5 17.9 (92) 14.5–21.2 57.6 (147) 51.5–63.8 50.9 (248) 46.5–55.4 25.1 (60) 19.6–30.6 24.8 (118) 20.9–28.7 
Socioeconomic status 
 Lives in developed cities/districts 7.4* (456) 6.7–8.0 16.8 (1033) 15.8–17.7 30.8* (140) 26.6–35.1 18.8 (194) 16.4–21.2 50.4 (207) 45.5–55.2 48.3 (459) 45.1–51.5 29.0# (120) 24.6–33.4 22.8 (212) 20.1–25.5 
 Lives in middle-developed cities/districts 7.4* (387) 6.7–8.1 17.4 (691) 16.2–18.5 30.7* (113) 26.0–35.4 20.6 (135) 17.5–23.8 54.6 (215) 49.6–59.5 53.4 (380) 49.8–57.1 26.1 (99) 21.6–30.5 22.5 (154) 19.3–25.6 
 Lives in developing cities/districts 5.9* (287) 5.2–6.5 15.3 (567) 14.2–16.5 35.7* (96) 29.9–41.5 20.0 (107) 16.6–23.4 51.5# (151) 45.8–57.3 43.3 (259) 39.3–47.3 28.0 (80) 22.7–33.2 24.4 (138) 20.9–28.0 
Total 6.7* (1163) 6.3–7.0 16.2 (2440) 15.6–16.8 31.9* (358) 29.1–34.6 19.6 (465) 18.0–21.2 51.8 (589) 48.9–54.7 48.7 (1176) 46.7–50.7 27.1* (302) 24.5–29.8 22.9 (533) 21.2–24.6 

aAmong students who had had sexual intercourse.

*,#Gender difference significant at P < 0.01, P < 0.05.

Associations between sexual intercourse, forced sex and demographic factors among high school students

When all of these variables were analysed with multiple logistic regressions, school type, family structure, maternal educational attainment, socioeconomic status were all found to be independently associated with self-report of having sexual intercourse for both girls and boys. For girls, school type and socioeconomic status were found to be independently associated with forced sex; for boys, the students who lived with others were 1.689 times more likely to have forced sex than males who lived with both parents (AOR = 1.689, 95% CI: 1.141–2.501); the students with mother of senior high school education were 0.628 times less likely to have forced sex than males with mothers of junior college or more education (AOR = 0.628, 95% CI: 0.489–0.806) and the students who lived in middle-developed cities or districts were 0.762 times less likely to have forced sex than males who lived in developing cities or districts (AOR = 0.762, 95% CI: 0.634–0.916) (Table 3).

Table 3

Multivariate logistic regression analysis of association between sexual intercourse, forced sexual intercourse and socio-demographic characteristicsa

 Sexual intercourse
 
Forced sexual intercourseb
 
 Female (n = 55177)
 
Male (n = 48638)
 
Female (n = 1418)
 
Male (n = 3572)
 
 AORc 95% CI AORc 95% CI AORc 95% CI AORc 95% CI 
Educational level 
 Grade 10 0.949 0.794–1.135 1.097 0.982–1.225 0.888 0.620–1.271 0.932 0.737–1.179 
 Grade 11 1.036 0.898–1.195 0.956 0.872–1.050 0.920 0.687–1.230 1.114 0.915–1.356 
 Grade 12         
School type 
 Key school 0.503 0.438–0.579 0.404 0.368–0.442 1.376 1.034–1.832 1.286 1.065–1.552 
 Ordinary school 0.516 0.452–0.588 0.551 0.507–0.598 1.457 1.114–1.906 1.032 0.865–1.232 
 Vocational school         
Family structure 
 Both parents         
 Single parent 1.783 1.510–2.104 1.508 1.348–1.688 1.053 0.748–1.481 0.874 0.687–1.112 
 One biological parent and one step parent 3.059 2.369–3.949 2.086 1.632–2.667 0.924 0.550–1.550 0.580 0.326–1.031 
 Grandparents 1.627 1.187–2.230 1.333 1.071–1.658 0.896 0.463–1.734 1.208 0.777–1.878 
 Other 3.114 2.336–4.151 1.722 1.402–2.114 1.035 0.581–1.844 1.689 1.141–2.501 
Maternal educational attainment 
 Junior high school or less 0.774 0.629–0.951 0.680 0.597–0.773 1.139 0.748–1.735 0.798 0.612–1.042 
 Senior high school 0.747 0.615–0.907 0.733 0.651–0.827 0.861 0.574–1.292 0.628 0.489–0.806 
 Junior college or more         
Paternal educational attainment 
 Junior high school or less 0.961 0.795–1.161 0.803 0.712–0.907 1.037 0.702–1.532 1.008 0.782–1.299 
 Senior high school 0.899 0.756–1.071 0.822 0.738–0.917 0.771 0.533–1.117 0.998 0.793–1.258 
 Junior college or more         
Socioeconomic status 
 Lives in developed cities/districts 1.404 1.228–1.606 1.153 1.056–1.259 0.524 0.399–0.690 0.838 0.698–1.007 
 Lives in middle-developed cities/districts 1.269 1.102–1.462 1.135 1.040–1.239 0.745 0.559–0.992 0.762 0.634–0.916 
 Lives in developing cities/districts         
 Sexual intercourse
 
Forced sexual intercourseb
 
 Female (n = 55177)
 
Male (n = 48638)
 
Female (n = 1418)
 
Male (n = 3572)
 
 AORc 95% CI AORc 95% CI AORc 95% CI AORc 95% CI 
Educational level 
 Grade 10 0.949 0.794–1.135 1.097 0.982–1.225 0.888 0.620–1.271 0.932 0.737–1.179 
 Grade 11 1.036 0.898–1.195 0.956 0.872–1.050 0.920 0.687–1.230 1.114 0.915–1.356 
 Grade 12         
School type 
 Key school 0.503 0.438–0.579 0.404 0.368–0.442 1.376 1.034–1.832 1.286 1.065–1.552 
 Ordinary school 0.516 0.452–0.588 0.551 0.507–0.598 1.457 1.114–1.906 1.032 0.865–1.232 
 Vocational school         
Family structure 
 Both parents         
 Single parent 1.783 1.510–2.104 1.508 1.348–1.688 1.053 0.748–1.481 0.874 0.687–1.112 
 One biological parent and one step parent 3.059 2.369–3.949 2.086 1.632–2.667 0.924 0.550–1.550 0.580 0.326–1.031 
 Grandparents 1.627 1.187–2.230 1.333 1.071–1.658 0.896 0.463–1.734 1.208 0.777–1.878 
 Other 3.114 2.336–4.151 1.722 1.402–2.114 1.035 0.581–1.844 1.689 1.141–2.501 
Maternal educational attainment 
 Junior high school or less 0.774 0.629–0.951 0.680 0.597–0.773 1.139 0.748–1.735 0.798 0.612–1.042 
 Senior high school 0.747 0.615–0.907 0.733 0.651–0.827 0.861 0.574–1.292 0.628 0.489–0.806 
 Junior college or more         
Paternal educational attainment 
 Junior high school or less 0.961 0.795–1.161 0.803 0.712–0.907 1.037 0.702–1.532 1.008 0.782–1.299 
 Senior high school 0.899 0.756–1.071 0.822 0.738–0.917 0.771 0.533–1.117 0.998 0.793–1.258 
 Junior college or more         
Socioeconomic status 
 Lives in developed cities/districts 1.404 1.228–1.606 1.153 1.056–1.259 0.524 0.399–0.690 0.838 0.698–1.007 
 Lives in middle-developed cities/districts 1.269 1.102–1.462 1.135 1.040–1.239 0.745 0.559–0.992 0.762 0.634–0.916 
 Lives in developing cities/districts         

aAmong high school students.

bAmong students who had had sexual intercourse.

cAdjusted for age.

Associations between sexual intercourse, high-risk sexual behaviours and demographic factors among college students

Multiple logistic regression models showed that for both girls and boys, the freshmen were less likely to have sexual intercourse than the seniors; the students who studied in junior college were less likely to have forced sex than those who studied in undergraduate college and students with mothers of junior high school or less education were less likely to have sexual intercourse and get pregnancy than students with mothers of junior college or more education. For girls, the freshmen were less likely to have sexual intercourse, but more likely to have high-risk sexual behaviours, such as forced sex, sex without a condom and unintended pregnancy than seniors; girls who lived with both parents were less likely to have sexual intercourse, forced sex and become pregnant; and girls who lived in developing cities or districts were less likely to have sexual intercourse than females who lived in developed or middle-developed cities or districts. For boys, the sophomores were less likely to have sexual intercourse, but more likely to have sex without a condom than the seniors; boys who lived with both parents were less likely to have sexual intercourse and forced sex and boys who lived in middle-developed cities or districts were more likely to have sexual intercourse, but less likely to have sex without a condom than males who lived in developing cities or districts (Table 4).

Table 4

Multivariate logistic regression analysis of association between sexual intercourse, high-risk sexual behaviours and socio-demographic characteristicsa

 Sexual intercourse
 
Forced sexual intercourseb
 
Sex without a condomb
 
Had been pregnant or gotten someone else pregnantb
 
 Female (n = 15877)
 
Male (n = 13354)
 
Female (n = 1068)
 
Male (n = 2118)
 
Female (n = 1067)
 
Male (n = 2157)
 
Female (n = 1055)
 
Male (n = 2082)
 
 AORc 95% CI AORc 95% CI AORc 95% CI AORc 95% CI AORc 95% CI AORc 95% CI AORc 95% CI AORc 95% CI 
Educational level 
 Freshmen 0.698 0.524–0.931 0.689 0.557–0.853 2.342 1.257–4.362 1.245 0.742–2.090 2.978 1.642–5.400 1.429 0.967–2.110 2.521 1.314–4.838 1.262 0.783–2.036 
 Sophomores 0.905 0.705–1.161 0.823 0.683–0.992 1.617 0.936–2.792 1.286 0.818–2.023 2.725 1.626–4.567 1.498 1.079–2.081 2.025 1.138–3.601 1.478 0.980–2.230 
 Juniors 1.102 0.866–1.401 1.072 0.892–1.288 1.459 0.851–2.501 0.945 0.601–1.485 1.815 1.096–3.006 1.149 0.837–1.577 1.436 0.814–2.534 0.859 0.568–1.300 
 Seniors                 
School type 
 Junior college 0.918 0.790–1.066 1.136 1.015–1.272 0.690 0.497–0.957 0.635 0.479–0.840 1.160 0.862–1.560 0.966 0.779–1.375 0.799 0.566–1.126 0.816 0.627–1.061 
 Undergraduate college                 
Family structure 
 Both parents                 
 Single parent 1.440 1.147–1.808 1.198 1.003–1.430 1.829 1.160–2.885 1.198 0.807–1.780 0.743 0.479–1.154 1.011 0.744–1.375 1.039 0.634–1.704 1.153 0.792–1.678 
 One biological parent and one step parent 3.393 2.341–4.919 1.508 0.967–2.352 0.888 0.414–1.906 1.284 0.503–3.280 0.653 0.311–1.374 1.029 0.510–2.074 0.667 0.285–1.563 1.034 0.401–2.670 
 Grandparents 1.617 0.986–2.650 1.396 0.952–2.048 0.778 0.270–2.243 1.712 0.779–3.765 0.995 0.365–2.715 1.088 0.516–2.290 0.507 0.142–1.813 1.022 0.437–2.392 
 Other 3.099 2.161–4.443 1.609 1.208–2.144 1.735 0.890–3.383 1.910 1.095–3.331 1.009 0.507–2.010 0.885 0.532–1.473 3.978 2.020–7.836 1.683 0.971–2.915 
Maternal educational attainment 
 Junior high school or less 0.569 0.451–0.717 0.540 0.449–0.650 0.736 0.463–1.171 1.025 0.662–1.587 1.104 0.707–1.724 1.277 0.912–1.788 0.537 0.329–0.875 0.583 0.393–0.864 
 Senior high school 0.622 0.498–0.778 0.694 0.579–0.833 0.673 0.430–1.055 1.034 0.675–1.584 0.928 0.602–1.429 1.080 0.777–1.501 0.655 0.409–1.048 0.691 0.473–1.012 
 Junior college or more                 
Paternal educational attainment 
 Junior high school or less 0.951 0.775–1.165 0.891 0.765–1.039 1.299 0.847–1.992 1.368 0.943–1.985 1.345 0.909–1.989 1.020 0.770–1.352 1.530 0.967–2.421 1.312 0.930–1.851 
 Senior high school 0.915 0.755–1.109 0.850 0.734–0.984 0.825 0.551–1.237 1.163 0.814–1.664 1.312 0.910–1.893 0.966 0.739–1.262 1.248 0.811–1.919 0.952 0.684–1.325 
 Junior college or more                 
Socioeconomic status 
 Lives in developed cities/districts 1.178 1.003–1.384 1.115 0.990–1.255 0.768 0.544–1.082 0.862 0.651–1.143 1.223 0.884–1.692 0.808 0.650–1.004 1.084 0.759–1.548 0.945 0.727–1.228 
 Lives in middle-developed cities/districts 1.290 1.097–1.517 1.160 1.023–1.316 0.762 0.535–1.085 1.063 0.786–1.436 0.892 0.646–1.227 0.650 0.517–0.817 0.905 0.629–1.303 0.934 0.708–1.232 
 Lives in developing cities/districts                 
 Sexual intercourse
 
Forced sexual intercourseb
 
Sex without a condomb
 
Had been pregnant or gotten someone else pregnantb
 
 Female (n = 15877)
 
Male (n = 13354)
 
Female (n = 1068)
 
Male (n = 2118)
 
Female (n = 1067)
 
Male (n = 2157)
 
Female (n = 1055)
 
Male (n = 2082)
 
 AORc 95% CI AORc 95% CI AORc 95% CI AORc 95% CI AORc 95% CI AORc 95% CI AORc 95% CI AORc 95% CI 
Educational level 
 Freshmen 0.698 0.524–0.931 0.689 0.557–0.853 2.342 1.257–4.362 1.245 0.742–2.090 2.978 1.642–5.400 1.429 0.967–2.110 2.521 1.314–4.838 1.262 0.783–2.036 
 Sophomores 0.905 0.705–1.161 0.823 0.683–0.992 1.617 0.936–2.792 1.286 0.818–2.023 2.725 1.626–4.567 1.498 1.079–2.081 2.025 1.138–3.601 1.478 0.980–2.230 
 Juniors 1.102 0.866–1.401 1.072 0.892–1.288 1.459 0.851–2.501 0.945 0.601–1.485 1.815 1.096–3.006 1.149 0.837–1.577 1.436 0.814–2.534 0.859 0.568–1.300 
 Seniors                 
School type 
 Junior college 0.918 0.790–1.066 1.136 1.015–1.272 0.690 0.497–0.957 0.635 0.479–0.840 1.160 0.862–1.560 0.966 0.779–1.375 0.799 0.566–1.126 0.816 0.627–1.061 
 Undergraduate college                 
Family structure 
 Both parents                 
 Single parent 1.440 1.147–1.808 1.198 1.003–1.430 1.829 1.160–2.885 1.198 0.807–1.780 0.743 0.479–1.154 1.011 0.744–1.375 1.039 0.634–1.704 1.153 0.792–1.678 
 One biological parent and one step parent 3.393 2.341–4.919 1.508 0.967–2.352 0.888 0.414–1.906 1.284 0.503–3.280 0.653 0.311–1.374 1.029 0.510–2.074 0.667 0.285–1.563 1.034 0.401–2.670 
 Grandparents 1.617 0.986–2.650 1.396 0.952–2.048 0.778 0.270–2.243 1.712 0.779–3.765 0.995 0.365–2.715 1.088 0.516–2.290 0.507 0.142–1.813 1.022 0.437–2.392 
 Other 3.099 2.161–4.443 1.609 1.208–2.144 1.735 0.890–3.383 1.910 1.095–3.331 1.009 0.507–2.010 0.885 0.532–1.473 3.978 2.020–7.836 1.683 0.971–2.915 
Maternal educational attainment 
 Junior high school or less 0.569 0.451–0.717 0.540 0.449–0.650 0.736 0.463–1.171 1.025 0.662–1.587 1.104 0.707–1.724 1.277 0.912–1.788 0.537 0.329–0.875 0.583 0.393–0.864 
 Senior high school 0.622 0.498–0.778 0.694 0.579–0.833 0.673 0.430–1.055 1.034 0.675–1.584 0.928 0.602–1.429 1.080 0.777–1.501 0.655 0.409–1.048 0.691 0.473–1.012 
 Junior college or more                 
Paternal educational attainment 
 Junior high school or less 0.951 0.775–1.165 0.891 0.765–1.039 1.299 0.847–1.992 1.368 0.943–1.985 1.345 0.909–1.989 1.020 0.770–1.352 1.530 0.967–2.421 1.312 0.930–1.851 
 Senior high school 0.915 0.755–1.109 0.850 0.734–0.984 0.825 0.551–1.237 1.163 0.814–1.664 1.312 0.910–1.893 0.966 0.739–1.262 1.248 0.811–1.919 0.952 0.684–1.325 
 Junior college or more                 
Socioeconomic status 
 Lives in developed cities/districts 1.178 1.003–1.384 1.115 0.990–1.255 0.768 0.544–1.082 0.862 0.651–1.143 1.223 0.884–1.692 0.808 0.650–1.004 1.084 0.759–1.548 0.945 0.727–1.228 
 Lives in middle-developed cities/districts 1.290 1.097–1.517 1.160 1.023–1.316 0.762 0.535–1.085 1.063 0.786–1.436 0.892 0.646–1.227 0.650 0.517–0.817 0.905 0.629–1.303 0.934 0.708–1.232 
 Lives in developing cities/districts                 

aAmong college students.

bAmong students who had had sexual intercourse.

cAdjusted for age.

Discussion

Main finding of this study

2005 CYRBS investigated the high-risk sexual behaviours among Chinese urban adolescents and found that 4.8% of grade 10–12 students and 11.3% of college students reported had ever had sexual intercourse. High school students who studied in key school had less sex but more forced sex than vocational school students, and students who lived in low socioeconomic areas had less sex but more forced sex than those who lived in higher socioeconomic areas. For college students, educational level, school type, family structure, maternal educational attainment and socioeconomic status were independently associated with at least one of the high-risk sexual behaviours. Freshmen had less sex but more high-risk sexual behaviours than seniors; students who lived with both parents had less sex and high-risk sex and students with mothers of junior high school or less education were less likely to have sexual intercourse and become pregnant than those with mothers of junior college or more education. Male students were significantly more likely to report sexual intercourse as most studies showed.13–15

What is already known on this topic

The proportion of grades 10–12 students (senior high school students) who had experienced sexual intercourse was much lower in China, compared with the US YRBSS in 2005 (4.8 versus 46.8%).15 And the proportion of grades 10–12 students who had experienced sexual intercourse was similar to that of adolescents aged 12–19 years in Guangdong in 2004 (4.8 versus 3.5%).14 It validated that China was still a conservative society whatever the economic level it reached. For the forced sexual intercourse, most of the research showed that both female and male youths were vulnerable to be forced to have sexual intercourse.16,17 2003 Youth Risk Behaviour Surveillance in the USA reported that 11.9% of female and 6.1% of male students had the forced sexual intercourse.18 We found a much higher proportion of students had experienced forced sexual intercourse, compared with the USA, while our prevalence was similar to the local studies, Liang et al.19 stated that in the Henan province, 3.4% of urban high school students had ever had sexual intercourse, and of these, 30.9% reported forced sex, and the most probable reason was the different social customs and cultural background. The prevalence of condom use among Chinese college students was much lower than those of American high school students15 (49.7 versus 62.8%), but similar to Hong Kong in 1999 (49.7 versus 49.8%).13 The prevalence of unintended pregnancy among Chinese college students was much higher than that of adolescents in Hong Kong (24.2 versus 9.6%).13

Similarly with Santelli et al.,20 and Manlove et al.,21 we also found that both male and female adolescents from non-intact families were also more likely to have had sexual intercourse, especially girls who lived without parents but others had more risk of having experienced high-risk sexual behaviours, such as unintended pregnancy than those who lived in both parent families. Different from the study conducted in Hong Kong, Lee and Tsang13 found that there was a significant inverse association between parental education and early sex, but we found that there was a significantly higher proportion of students with parents with a higher educational background who reported experience of sexual intercourse, and Wang et al.14 showed results similar with ours. Students whose parents with junior college or with more educational background were more likely to have sexual intercourse, forced sex and experience unintended pregnancy, and we presumed that parents with higher educational background perhaps have less time and responsibility to educate and communicate with their children, but more evidence is needed for explanation.

What this study adds

In our study, we noticed that grade 10–12 students who studied in key school had less sex but more forced sex; we should explain that key school in China meant better learning environment, better resources, and limited in quantity, and for the numerous students in China, only excellent students with outstanding academic records could have the chance to study in key schools. So what we found in this survey reflected three facts: first, a better learning environment could help to postpone the time of first sexual intercourse; second, students who studied in a better learning environment were relative elitists, and they usually had great foresight and good self-control, and third, students also demanded the sex education on how to protect themselves from high-risk sexual behaviours, even those who studied in key school. On the contrary, the vocational school in China meant poor resources and students with poor school performance and lowest academic records. What we should do on in this population is to postpone the time of their first sexual intercourse and teach them skills of self-protection and safe sex.

What deserves to be mentioned the most was, the lower economically the city or district the adolescents lived, the lower the prevalence of having sexual intercourse, the higher the prevalence of having forced sexual intercourse and the lower the prevalence of condom use reported. It revealed that the lower economically the city or district, the more the conservative cultural background and the lesser the information about self-protection, thus fewer students had sexual intercourse, at the same time, there was more forced sexual intercourse among students who had sexual intercourse and the fewer students had used a condom. So even in the developing city or district, where the prevalence of sexual intercourse was very low, we also need sexual education to teach adolescents about protecting themselves from being victims of high-risk sexual behaviours.

Since social, economic and political forces are rapidly changing the ways that young people must prepare for adult life, especially in the developing countries such as China, adolescents are expected to spend more time in school, marry and have children later than before for a better material life. So school will be the best place to teach them how to plan their lives, including setting great sights for the future, staying from health-risk behaviours, selecting a health life style, postponing the first sexual intercourse and maintaining a good mood and emotion, etc. As we found in our study, the better the school environment in which the students studied, the less the sexual intercourse reported, so with the family with both parents, thus reinforcing the importance of school and family as support networks for young people. Carter et al.22 also found that school engagement showed the strongest and most pervasive associations across both health-compromising and -promoting behaviours. School may well play an especially important role in reproductive health among young people.

Limitations of this study

Despite many strengths of our study, there are also some limitations warranting discussion. One limitation is lack of data from rural adolescents and adolescents out of schools; however, rural students were more than urban students in China (67 versus 33%),2 and when adolescents finished their nine-year-system compulsory education, more than half of them drop out of school, which may underestimate the prevalence of sexual behaviours among Chinese adolescents, because some literatures showed that the sexual behaviours were higher among rural adolescents compared with urban adolescents, and higher among adolescents who drop out of school, compared with students.3,23–25 Another limitation of this study is that it was a cross-sectional one, so we cannot track trends over time; we could only draw an associated conclusion, and all we found from this study implied a probability, not a causal conclusion.

Conclusion

This study highlights the association among high-risk sexual behaviours and school type and socioeconomic status. We confirmed that adolescents who studied in different school types have different performance on sexual intercourse. Key school students had less sex but more forced sex. Vocational school students should be the target group of reproductive health education because of high prevalence of sexual intercourse among this population. We disproved our hypothesis that adolescents who lived in the developed socio-economic areas had more high-risk sexual behaviours, in fact, adolescents who lived in developing areas performed more high-risk sexual behaviours, and should be provided self-protection education and skills. We also ascertained that adolescents with parents who had less educational background had less sexual intercourse. In addition, we found that students who lived in intact families were less likely to have sexual intercourse than those who lived in non-intact family, and it hinted that an intact family also played an important role in postponing the early sex, as well as decreasing high-risk behaviours.

Supplementary data

Supplementary data are available at the Journal of Public Health online.

Funding

This study was funded by the Ministry of Health, P. R. China. Data collection was supported by the local Centers for Disease Control and Prevention.

Acknowledgements

We thank all investigators and officials from local CDCs for their contributions to data collection. We also thank the teachers and students at high schools and colleges who participated in this study for their cooperation. This study went through IRB reviewing process in China and was approved by the School of Public Health, Peking University, People's Republic of China.

References

1
UNICEF, UNAIDS and WHO
Young People and HIV/AIDS: Opportunity in crisis.
 , 
2002
New York
UNICEF
2
Xue
L
Guo
SF
Wang
LH
, et al.  . 
The current situation of reproductive health among Chinese adolescents (in Chinese)
Matern Child Health Care China
 , 
2004
, vol. 
19
 
8
(pg. 
122
-
3
3
Wellings
K
Collumbien
M
Slaymaker
E
, et al.  . 
Sexual behavior in context: a global perspective
Lancet
 , 
2006
, vol. 
368
 
11
(pg. 
1706
-
28
)
4
WHO
Towards Adulthood: Exploring the Sexual and Reproductive Health of Adolescents in South Asia
 , 
2003
Geneva
World Health Organization
5
WHO
Prevention and Control of Sexually Transmitted Infections: Draft Global Strategy.
 , 
2007
Geneva
World Health Organization
6
Population Council
The Adverse Health and Social Outcomes of Sexual Coercion: Experiences of Young Women in Developing Countries
 , 
2004
New York USA
Population Council
7
Ceballos
GA
Campo-Arias
A
Sexual intercourse among adolescent students of Santa Marta, Colombia: a cross-sectional survey*
Colomb Med
 , 
2007
, vol. 
38
 
3
(pg. 
191
-
6
)
8
Hallfors
DD
Waller
MW
Ford
CA
, et al.  . 
Adolescent depression and suicide risk: association with sex and drug behavior
Am J Prev Med
 , 
2004
, vol. 
27
 
3
(pg. 
224
-
31
)
9
Martin
G
Bergen
HA
Richardson
AS
, et al.  . 
Sexual abuse and suicidality: gender differences in a large community sample of adolescents
Child Abuse Negl
 , 
2004
, vol. 
28
 
5
(pg. 
491
-
503
)
10
Herrera
A
Dahlblom
K
Dahlgren
L
, et al.  . 
Pathways to suicidal behaviour among adolescent girls in Nicaragua
Soc Sci Med
 , 
2006
, vol. 
62
 
4
(pg. 
805
-
14
)
11
The Editorial Office of China Education Yearbook
China Education Yearbook 2007 (in Chinese)
 , 
2007
Beijing
People's Education Press
12
Ji
CY
Report of 2005 National Youth Risk Behavior Survey in China (in Chinese)
 , 
2007
Beijing
Peking University Medical Publications
13
Lee
A
Tsang
CKK
Youth risk behaviour in a Chinese population: a territory-wide youth risk behavioural surveillance in Hong Kong
Public Health
 , 
2004
, vol. 
118
 
2
(pg. 
88
-
95
)
14
Wang
J
Deng
XJ
Wang
JJ
, et al.  . 
Substance use, sexual behaviours, and suicidal ideation and attempts among adolescents: findings from the 2004 Guangzhou Youth Risk Behaviour Survey
Public health
 , 
2009
, vol. 
123
 
2
(pg. 
116
-
21
)
15
Eaton
DK
Kann
L
Kinchen
S
, et al.  . 
Youth risk behavior surveillance—United States, 2005
J Sch Health
 , 
2006
, vol. 
76
 
7
(pg. 
353
-
72
)
16
Buzi
RS
Tortolero
SR
Roberts
RE
, et al.  . 
Gender differences in the consequences of a coercive sexual experience among adolescents attending alternative schools
J Sch Health
 , 
2003
, vol. 
73
 
5
(pg. 
191
-
6
)
17
Basile
KC
Black
MC
Simon
TR
, et al.  . 
The association between self-reported lifetime history of forced sexual intercourse and recent health-risk behaviors: findings from the 2003 National Youth Risk Behavior Survey
J Adolesc Health
 , 
2006
, vol. 
39
 
5
(pg. 
752.e1
-
752.e7
)
18
Grunbaum
JA
Kann
L
Kinchen
S
, et al.  . 
Youth Risk Behavior Surveillance—United States, 2003
MMWR Surveill Summ
 , 
2004
, vol. 
53ss-2
 (pg. 
1
-
96
)
19
Liang
ZS
He
J
Yang
BS
, et al.  . 
Study on sexual behavior and relative factors among city high school students (in Chinese)
J Med Forum
 , 
2008
, vol. 
29
 
14
(pg. 
59
-
61
20
Santelli
JS
Lowry
R
Brener
ND
, et al.  . 
The association of sexual behaviors with socioeconomic status, family structure, and race/ethnicity among US adolescents
Am J Public Health
 , 
2000
, vol. 
90
 
10
(pg. 
1582
-
8
)
21
Manlove
J
Ikramullah
E
Mincieli
L
, et al.  . 
Trends in sexual experience, contraceptive use, and teenage childbearing: 1992–2002
J Adolesc Health
 , 
2009
, vol. 
44
 
5
(pg. 
413
-
23
)
22
Carter
M
McGee
R
Taylor
B
, et al.  . 
Health outcomes in adolescence: associations with family, friends and school engagement
J Adolesc
 , 
2007
, vol. 
30
 
1
(pg. 
51
-
62
)
23
Zhu
GR
Ji
CY
Song
Y
, et al.  . 
A qualitative study on HIV/AIDS related knowledge and attitude among mobile adolescents (in Chinese)
Chinese J School Doctor
 , 
2003
, vol. 
17
 
2
(pg. 
112
-
4
24
Song
Y
Ji
CY
Xing
Y
, et al.  . 
Sexual behaviors among urban senior middle school students in 18 Provinces in China (in Chinese)
Chinese J School Health
 , 
2008
, vol. 
29
 
12
(pg. 
1079
-
81
25
Song
Y
Ji
CY
Xing
Y
, et al.  . 
Survey on the sexual behaviors of Chinese College Students (in Chinese)
Chinese J School Health
 , 
2009
, vol. 
30
 
2
(pg. 
116
-
21

Supplementary data