This systematic review is a comprehensive and up-to-date assessment of the causes of high-risk behaviors and protective factors against them. To do the assessment, we identified 743 papers published from 2000 to 2021. After investigating the titles, abstracts, and standards based on the systematic review format suggested by Moher et al., 45 articles remained for the final analysis (
7). The results were categorized into individual, family, social, and spiritual categories.
Individual factors have been defined, measured, and operationalized differently in different papers among the most critical protective and risky factors. For example, Castro (
9) focused on reducing risk perception during the relationship. However, Woerner et al. focused on the sensitivity to rejection (
22). In any case, regardless of the definition and measurement of individual variables, they affect the occurrence of high-risk sexual behaviors (
16,
20). Considering the sensitivity to rejection, contexts peers are involved in seem to worsen the issue. Such situations make people vulnerable to high-risk behaviors by provoking emotional and physiological reactions (
22). Although some studies associate this rejection with emotionally and physically invalidating experiences in childhood (
9), others state that it is the result of the lack of sexual assertiveness (
11).
Identity issues and engaging in risky sexual behaviors were the common findings of all studies. However, the studies merely focused on emotional and physiological reactions and did not suggest any recommendations about how a person should deal with social rejection, and emotional issues as an individual component have enough scientific and research evidence. This can be considered a significant growth factor in people's growth process. This factor was also defined, measured, and operationalized with different methods in different studies. For example, some studies defined emotional invalidation as sexual abuse in childhood (
18). Some defined it as negligence (
15), and others defined it as physical violence (
27). These developmental experiences could include the divorce of parents in childhood, which was mentioned in few studies (
25). These studies focused on negative childhood experiences' role in regulating emotions. However, nothing was mentioned about how this emotional regulation prevents a person from risky behaviors.
Sexual curiosity was also considered an essential factor. At the beginning of the activation of sexual desire, people generally look for those sexual relationships that require no obvious commitment. First, they use online and offline channels for sexual activities and prepare themselves for physical intercourse. Digital channels create a safe margin to satisfy their curiosity and access to sexual stimuli, leading them to perform physical sexual behaviors. Individuals start with a tentative sexual image of themselves and then move on to real relationships. In this regard, some research reveals that when individuals start sexual curiosity at an early age, they seek more sexual excitement when they get older (
17). Studies do not provide anything about the situations in which sexual curiosity is considered inappropriate or normal or the age at which it is normal. But it seems that to channel this curiosity toward natural age-appropriate behaviors, we need more research to make a better decision.
The reduction of risk perception during intercourse has also been reported as a risk factor in studies. The study by Castro showed that among 1,452 university students, 87% experienced vaginal penetration, and 20% experienced anal intercourse. In addition, in both cases, reluctance to use preventive measures and drug and alcohol consumption were also observed. A significant majority of these people had experienced cases of sexually transmitted infections and sexual problems. Such infections were investigated in different studies. Some researchers examined people's blood in a laboratory, and others used questionnaires (
9). Castro used a university laboratory and found that some of these people were unaware of their infection and that it could be transmitted to others. However, the studies did not say anything about the reason for students' risky behavior and reluctance to use preventive measures, despite being educated and informed. Another study stated that being employed and participating in productive economic activities is an essential barrier against risky sexual behaviors (
35). Nevertheless, we still need more research to conclude in this area. Studies must also consider other factors because being active in society can facilitate communication and access to sexual partners. The studies do not present information about which jobs act as obstacles, whether people voluntarily delay this action, or whether this issue is one of their job requirements.
Another critical factor was low self-esteem and negative sexual self-concept. In this regard, Lacelle et al. showed that low self-esteem and inappropriate sexual self-concept are among the causes of high-risk sexual behaviors (
18). Studies revealed that low self-esteem causes emotional problems in people and leads to loneliness (
20). Loneliness makes people vulnerable and susceptible to risky sexual behavior. If we consider emotional problems and loneliness as the result of low self-esteem and inappropriate sexual self-concept, then it is likely that these people engage in online sexual activities or alcohol consumption (
16,
19). Again, no specific suggestion was given on how to deal with loneliness. However, in the studies that pointed to the protective role of individual factors, the role of health literacy was emphasized. For example, in Darteh et al, health literacy was considered a protective factor (
35). Also, Aspy al. mentioned that "saying no," as one of the components of health literacy, can protect people from such behaviors (
11). However, there is no consensus on whether assertiveness causes people to say no or whether their personality traits make them assertive. In any case, more studies are needed to decide on this field.
Family factors are also considered both protective and risky factors in the occurrence of high-risk sexual behaviors. In the studies, a strong family foundation was a powerful shield against risky sexual behaviors. However, there were many differences in the methods of measurement and definition. Inconsistencies were also observed in the quality of measurements. Regarding the sub-components of the family foundation, it seems that parent-child dialogue in a safe environment positively affects managing risky sexual behaviors. This is a significant factor not seen in dysfunctional families (
25). When family members perceive high levels of family bonding, the effect of parental monitoring on sexual behaviors increases because children better accept such parental monitoring. This can be part of an authoritative parenting strategy. Therefore, studies consider the relationship between parents and children as an essential care factor in preventing high-risk behaviors (
11). Supportive behaviors provided by parents create a sense of belonging and positively impact children's sexual relationships. Of course, the research emphasizes improving communication and sexual assertiveness skills in the family because early, and multiple sexual experiences become the basis for later adulthood behaviors (
9).
Regarding the optimal family foundation, studies reveal similar results. Dysfunctional families were considered one of the essential factors in high-risk sexual behaviors. For example, living with a single parent and single-parent dating are essential factors in the occurrence of high-risk sexual behaviors (
25). As mentioned before, there is little supervision over children's behavior in such families, and they hardly accept it, especially when they see parents dating. On the other hand, excessive parental control can also lead to the risk of sexual behaviors. Although research findings showed that risky sexual behaviors are related to the parent-child relationship, this issue is not considered in dysfunctional families (
23,
28). In such families, there is no agreement on child-rearing and parenting issues. Studies have thoroughly investigated this issue and provided strong evidence.
Social factors can also be important in the occurrence and prevention of high-risk sexual behaviors. For example, lack of proper education, inefficient social support, and having friends with risky sexual behavior was regarded as social factors. Even though these social factors make people vulnerable to risky sexual behavior, social protective factors emphasize sex education and health literacy. We can define health literacy as the degree to which individuals can obtain, process, and understand basic health information needed to make appropriate health decisions (
35). Therefore, access to education and health literacy is considered one of the critical protective factors. Studies in this field emphasize such access in the family, school, and society. Programs considering the relationship between families and teenage members reported that parents' actions had a positive effect. For example, in an educational program aimed at youth development and educating parents about positive parenting methods, effective communication and active participation in sex education were proven to have positive impacts (
32). Other programs used role-playing strategies to strengthen parent-child social and sexual communication. Spending time with peers who are responsible and sociable can have a positive effect on sexual relationships. However, studies did not mention how we can access proper education, and it seems we face limitations in obtaining this information. In any case, changes in school policy and interactive classroom education can lead to managing these behaviors. However, we need interventional research in this field because cultural sensitivities are essential to this factor.
Finally, the spiritual factor is an important protective factor. Studies reported that being in contexts that do not support religious beliefs is a risk factor. However, people who were faithful or those whose parents had religious beliefs were reported to be safe from sexually risky behaviors. Studies used several methods in defining religion, which naturally affected measuring religious attitudes. However, research reported that religion is a decisive factor in preventing risky sexual behaviors (
24,
36,
42,
45).
To sum up, it seems that the factors investigated in the studies interact with each other. Therefore, the joint actions of families, schools, and society can effectively deal with such behaviors. These steps should be made to protect future generations as a social resource. But to achieve this, we must first become more knowledgeable in this area and be aware of the problems and cultural sensitivities in treatment and prevention strategies. Furthermore, it is critical to realize that these behaviors evolve naturally as children grow, and on the other hand, young people are becoming more independent and experienced. Therefore, looking at all age groupings over time is essential to understand their contexts, circumstances, communication needs, and care requirements.