The present study found that, compared to their peers of general residents, adolescents of migrant workers were more prevalent in sexual intercourse during lifetime (7.2% vs, 4.5%) and sexual intercourse during the last three months (4.3% vs, 1.8%). Among the adolescents with a history of sexual intercourse in last three months, more adolescents of migrant workers reported unprotected intercourse (47.3% vs, 34.3%). Moreover, our study demonstrated that, compared to their peers of general residents, adolescents of migrant workers tended to have sexual intercourse in younger age and more frequent cigarette smoking (as shown in Table ). There results indicated that, compared to their peers of general residents, adolescents of migrant workers were at greater risk for HIV/STI.
A number of studies in China revealed that the prevalence of lifetime sexual intercourse ranged from 1.3% to 4.8% in general junior school students [21
], which was consistent with the results of our study in adolescents of general residents. In studies of other countries, adolescents who ever had sexual intercourse were 48.7% in America (aged 10–24 years) [30
], 38% in Italy (aged 14–19 years) [31
], 17–46% in South Africa (aged 13–17 years) [32
], 11% in Burkina Faso (aged 12–19 years) [33
], 18–22% in Nigeria (aged 15–19 years) [34
], and 5.1–56.6% in Turkey (aged 16–20 years) [35
], which was higher prevalent than our sample (aged 11.08–16.67 years). The disparity may be due to different sample characteristics, different traditional cultural background, and different socioeconomic environment. For example, compared to the Western countries, Chinese society has a strong tradition of Confucianism, in which conservative values are prevailed. In such a traditional culture, abstinence is emphasized for unmarried people, especially for females, which is considered to be linked to personal and family honor. The intrinsic sociocultural values may partly explain the lower prevalence of sexual intercourse in Chinese adolescents.
Previous studies revealed that many factors were associated with adolescents' sexual intercourse: age, ethnicity, gender, substance use, family structure and socioeconomic status [13
]. For example, a recent study in Ethiopia youth indicated that lower socioeconomic status and restricted educational were risk factors for high-risk sexual behaviors [17
]. Adolescents of migrant workers mostly lived in an unstable and poor economic environment, which prevent them from getting regular and high quality education and health care. Our survey showed that, compare to their peers of general residents, adolescents of migrant workers were poor in knowledge on sex/HIV/STI and lower in awareness to risk behaviors (Table ). In additional, our survey found that 18.7% of families was single parented in adolescents of migrant workers, which may lead to less parental caring, love, and monitoring for them and then resulted in more risk behaviors. The clustering of risk factors may partly or totally account for the differences in sexual behaviors and substance use between adolescents of migrant workers and their peers in general residents. It should be specially emphasized that unprotected sex in our sampled adolescents, especially in adolescents of migrant workers, was more prevalent than their peers of other countries [30
], which indicated a higher level of vulnerability to a range of undesirable consequences associated with sexual activity, including HIV, STI, even unintended pregnancy.
To best address sexually related public health concern for adolescents, it is crucial to reveal the correlating factors, especially for higher-risk groups, in China. Consistent with previous studies, our study found that sexual behaviors were a multifactorial issue. In the present study, it was demonstrated that five variables were significantly associated with sexual intercourse in last three months for adolescents of migrant workers: older age, lower family income, younger age at first sexual intercourse, lower knowledge on HIV/AIDS, and fewer communication.
Among all the factors identified associated with sexual intercourse in last three months for adolescents of migrant workers, poor family income had the highest OR. Our survey showed that nearly one-half of families lived in extremely poor condition, with an average family income < 1000 RMB (yuan)/person/month. Such lower economic status could undoubtedly prevent children from having basic health care and educational improvement. Under the current educational system in China, education in primary school and junior high school was free-feed and compulsory, however, for a long time, children of migrant workers were excluded from the compulsory educational scheme in urban area. Although the problem was gradually resolved from last year in Shangai, children of migrant workers still face barriers to accessing regular education because of parents' frequent migrant. Therefore, although most schools provide HIV/STI education, children of migrant workers are unlikely to receive school-based intervention. That may be why our study found that lower knowledge on HIV/AIDS and fewer communication were strong factors associated with sexual intercourse in last three months for adolescents of migrant workers.
There are several limitations that should be considered in interpreting these results. Firstly, social-desirability bias and inaccuracy may be existed in answering the questionnaires despite guaranteed anonymity. Secondly, because the sample was not large enough, the analyses were not conducted by dividing the sample by age. As the age-range is quite spread, it would be possible that different factors are associated to risk sexual intercourse according to the age. Thirdly, China is a multi-ethnical country (56 ethnic groups) with a population of 1.3 billion (90.56% Han ethnicity vs, 9.44% other ethnicity named ethnic minority, such as Muslim ethnicity, Mongolia ethnicity, Uighur ethnicity, and etc). It is possible that, although may be very small, migrant workers were likely to be from ethnic minority. It was a pity that our study did not investigate the information on ethnicity of sampled participants. The forth limitation lies in the fact that our findings regarding migrant adolescents were much more so within the local-national environment and may not reflect the practice in other countries. In addition, the sample of adolescents of migrant workers was small, which may weaken the strengths of the study. The fifth limitation existed in study design. The cross-sectional nature of the study made it difficult to determine a causal relationship. Finally, our sample limited our analyses of demographic subgroups and can not be generalized to other population.