The age of adolescence is a transition period from childhood to adulthood. Adolescence is characterized by significant physiological, psychological and social changes that put adolescents at high risk for sexual and reproductive health (SRH) problems . Therefore, adolescent reproductive health is an important issue that impacts national development . The is due to the number of adolescents in Indonesia, approximately 19.5%,  and in West Java about 18.7% of the total population .
There are three main problems in adolescent reproductive health. They were sexuality, substance abuse and sexually transmitted infections (STIs), including the human immune deficiency virus and acquired immune deficiency syndrome (HIV/AIDS). Sexuality is a crucial problem for teenagers, especially girls. This problem can arise due to early sexual activity or marriage at a young age, sparked by culture. Approximately 26.5% of women marry in their teens . For a girl, pregnancy is a consequence of sexual behavior. Some sources indicate high rates of pregnancy in adolescents [6,7]. Complications that may occur due to adolescent pregnancy include increased incidence of maternal death [6,8] and neonatal mortality .
The early initiation of sexual activity means an adolescent faces an increased risk of STIs, HIV/AIDS, unwanted pregnancy and unsafe abortion . The incidence of AIDS in adolescents is high . Other high-risk behaviors are drug and substance abuse, including smoking. Smoking is closely related to non-communicable diseases such as cardiovascular disease, chronic obstructive pulmonary disease, and cancer . Results of the National Narcotics Survey showed that about one million drug users were in their teens . These risk behaviors increased the chance of engaging in premarital sexual intercourse  and also increased exposure to STIs and HIV/AIDS [12,14]. Needle-sharing also enhanced the risk of disease transmission .
Adolescents that live in the North Coastal line have a high risk associated with reproductive health because the entertainment industry and prostitution business in the area creates an unfavorable environment for adolescents. Environmental-based diseases such as HIV/AIDS have increased in this district, and the cases mostly in the sub-districts of the North Coastal line [15,16,17]. The young marriage culture in this area is also strong. The high rate of divorce and the number of mothers who become Indonesian women laborers working abroad weakens the role of parents in character building and the moral education of adolescents. It allows adolescents to fall into sexual activity, drug use and sexually transmitted infections .
Poor social and cultural conditions that not balanced with useful information will encourage adolescents to choose unhealthy sexual and reproductive behaviors. Thus, access to information and education in sexual and reproductive health is critical to enable teens to protect their health and empower them to use their sexual and reproductive health rights . However, there is not enough information about reproductive health. It is essential to determine the current level of adolescent reproductive health knowledge so programs and health services can meet their needs. Therefore, the purposes of this study were to gain insight into the characteristics of adolescents in the North Coast Line and their families and also to assess the baseline reproductive health knowledge of the adolescents. Thus, the interventions suggested based on their needs.
A cross-sectional study conducted in Pusakajaya Junior High School 1 and 2 of the Subang District from August until December 2016. This location purposely selected because of the Pusakajaya sub-district nearby including the Patimban and Genteng prostitution areas. Respondents chose by using purposive sampling, in which 269 seventh grade students (male=135, female=134) were interviewed using a semi-structured questionnaire.
Permission was obtained from the Principal of the Junior High Schools and informed written consent obtained from the subjects. Confidentiality and anonymity assured for all the interviewees. Adequate measures were observed to ensure objectivity in the data collection. The collected data was compiled, stating the frequency of every response for each item and then transcribed onto a master sheet. Statistical analysis done by calculating the percentages of each rate. Percentages were calculated to draw out the differences in the responses and to highlight significant responses. Data analyzed using univariate analysis. Tables and graphs were drawn to demonstrate the results of the present study.
Demographic and family characteristics
Since the interviews conducted with a susceptible age group, the questions of sexual and reproductive health were positioned late in the questionnaire. The conversation started with very general questions on their demographic characteristics.
The age of the respondents was early adolescent, and the number of male and female were balanced. There were 17.1% living with a single parent and 19.7% with relatives. Most of the adolescents confessed to being less obedient regarding religiosity. About 59.1% had the poor motivation to do well in school, and 79.6% were not actively engaged in school.
Approximately 15.6% of the parents of the adolescents were divorced. Often the number of family members were large (about 44.4%). Most parents of the adolescents had low education levels (father 83.6% and mother 91%), and 6.7% of the fathers of the adolescents were unemployment. While 21.6% of the mothers of the adolescents worked as Indonesian women laborers.
Reproductive health knowledge
The adolescents' level of knowledge about reproductive health was poor in all categories. The results showed 90.3% (male=40.9%; female=49.4%) for signs of female puberty, 99.6% (male=49.8%; female=49.8%) for signs of male puberty, 100% for the risk of adolescent pregnancy, 89.2% (male=43.9%; female=45.3%) for HIV/AIDS, 98.1% (male=48.7%; female=49.8%) for sexually transmitted infections and 99.3% (male=49.4; female=49.8%) for the risk of smoking and substance abuse (Table 3).
Motivation and active engagement in school, religiosity, and living with both parents can protect young people from taking risks . The findings of this research showed that many of the adolescents who were less obedient regarding religiosity had poor motivation and engagement in school. A number of the teenagers did not live with both parents because their parents were divorced or worked out of town, and therefore had less supervision. These negative characteristics could encourage them to engage in high-risk behaviors.
Most parents of the adolescents had low education levels, and some had lower economic status because of their occupation. To get a higher salary, some mothers worked as Indonesian women workers abroad. The had an impact on their children's education. Families with these characteristics may increase the risks for their children by devaluing education and encouraging early marriage and childbearing. Families with low education levels may also discourage adolescents from seeking information and services .
Similar to previous studies [1, 22, 23], adolescents in the North Coastal line had a lack of knowledge about reproductive health. It can lead them to unhealthy behaviors. Knowledge about reproductive health is essential to enable adolescents to make healthy decisions so that they can guard their health.
Therefore, it is essential to strengthen the knowledge and skills of the adolescents to help them make healthy decisions about reproductive health. This effort can make by providing reproductive health education in schools, as well as out of school. A positive social environment is also essential to encourage adolescents to choose a healthy lifestyle. Health service centers for adolescents to obtain information are also important.
Most of the adolescents had negative characteristics, including poor motivation to do well in school and also less engagement in school. Some of them did not live with their parents. The family characteristics of the adolescents were also negative. Many of their parents were divorced, most of the parents also had a low education level and lowered the salary in their occupations. The adolescents had poor knowledge in all categories of reproductive health, including signs of puberty, STI, HIV/AIDS, smoking and substance abuse risks. Hence, it is essential to improve the knowledge of adolescents' experience by giving them an appropriate education about reproductive health.
I want to thank the school principal, teachers and especially the seventh-grade students at Pusakajaya Public Junior High School 1 and 2.