Table A4.

Study characteristics.

Study	Country	Aim	Type of Study	Population and Sample	Interventions	Key Findings
(Hirvonen et al., 2021)	UK	To understand the perceptions of adolescent students regarding the use of Facebook social media in sexual and reproductive health learning.	Mixed methods	1413 teenagers (14 to 16 years)	Combined interventions: peers’ intervention and use of private Facebook groups	Social media groups formed around peer supporters’ existing friendship networks hold potential for diffusing messages in peer-based sexual health interventions.
(Alhassan et al., 2019)	Ghana	To assess mobile phone usage among adolescents and young adult populations pursuing tertiary education and their use of these technologies in the education and prevention of STI.	Quantitative	250 teenagers (18 to 24 years)	Mobile phone interventions	Future mobile phone programs should be considered for STI education and prevention, as they were found to be more comfortable than traditional messaging or phone calls.
(Cornelius et al., 2019)	USA	To examine adolescents in the USA and Botswana, their mobile phone and social media usage, and their perceptions of safer-sex interventions delivered via social media.	Qualitative	28 teenagers (13 to 18 years)	Mobile phone interventions	Findings provided a starting point for researchers interested in developing a social media intervention with global implications for sexual health promotion.
(Golbasi and Taskin, 2009)	Turkey	To evaluate the effectiveness of school-based reproductive health education for adolescent girls on the reproductive knowledge level of the girls.	Quasi- experimental	189 adolescents (age not mentioned)	Sex education sessions	The school-based program was conducted by nursing educators, and the program was effective in increasing the students’ levels of knowledge on reproductive health.
(Richards et al., 2019)	Dominican Republic	To evaluate the effectiveness of MAMI’s CSEP in changing knowledge of STIs and pregnancy.	Mixed methods	600 students aged 11–25 years old	Multiple interventional program (comprehensive sexual education program: education sessions, interactive activities, visual aids)	The MAMI’s CSEP improved knowledge of STIs and pregnancy and attitudes toward risky sexual behavior among program recipients.
(Yakubu et al., 2019)	Ghana	To assess an educational intervention program on knowledge, attitude, and behavior toward pregnancy prevention based on the HBM amongst adolescent girls in Northern Ghana.	RCT	363 adolescents (13 to 19 years).	Sex education sessions	Educational intervention, which was guided by HBM, significantly improved sexual abstinence and the knowledge of adolescents on pregnancy prevention.
(Aragão et al., 2018)	Brazil	To understand the perceptions of adolescent students regarding the use of Facebook social media in sexual and reproductive health learning.	Qualitative	96 adolescents (mean age 15 years)	Online interventions (Facebook)	Virtual spaces on the Internet offer potential for the production of health care, especially among adolescents, as it contributes to the sexual and reproductive health education in an interactive, playful, and practical way.
(Bersamin et al., 2018)	USA	To investigate the associations between SBHCs and sexual behavior and contraceptive use among 11th graders.	Quantitative	11840 adolescents (average age 16.6)	Interventions delivered through SBHCs	Exposure to SBHCs in general, and availability of specific reproductive health services, may be an effective strategy to support healthy sexual behaviors among youth.
(Hickman and Schaar, 2018)	USA	To develop and evaluate adolescent satisfaction with a text-messaging educational intervention to promote healthy behaviors, reduce the incidence of unhealthy behaviors, and prevent high-risk behaviors.	Mixed methods	202 adolescents (14 to 18 years)	Mobile phone interventions	Text messaging is a good way to educate adolescents and promote healthy habits, as it shows a high rate of intended behavioral change by adolescents.
(Beserra et al., 2017)	Brazil	To analyze the perception of adolescents about the life activity “express sexuality”.	Qualitative	25 teenagers (15 to 18 years)	Combined interventions: video projection followed by discussion and clarification of doubts	The use of videos followed by discussion is a valid and useful strategy to help adolescents in expressing their sexuality.
(Rokicki et al., 2017)	Ghana	To evaluate whether text-messaging programs can improve reproductive health among adolescent girls in low- and middle-income countries.	RCT	756 adolescents (14 to 24 years)	Mobile phone interventions	Text-messaging programs can lead to large improvements in reproductive health knowledge, and have the potential to lower pregnancy risk for sexually active adolescent girls.
(Santos et al., 2017)	Brazil	To report the experience of conducting a workshop with teenagers about STIs.	Qualitative	34 adolescents (average age, 18 years old)	Workshops	Group educational experiences provide adolescents with the opportunity to build shared knowledge, and professionals learn about adolescents’ doubts, and therefore plan new health education meetings.
(Souza et al., 2017)	Brazil	To describe the online game and reflect on its theoretical– methodological basis.	Qualitative	60 adolescents aged 15–18 years	Online game (Straight Talk)	Conceived as a pedagogic device, the online game has the capacity to implicate the adolescent in problem-based situations and allows the invention of other forms to deal with sexuality without the demand of support from a teacher.
(Castillo-Arcos et al., 2016)	Mexico	To evaluate the effect of an internet-based intervention to reduce sexual risk behaviors and increase resilience to sexual risk behaviors among Mexican adolescents.	Quasi- experimental	193 adolescents (14 to 17 years)	Online interventions (sex education sessions)	The intervention improved self-reported resilience to risky sexual behaviors, though not with a reduction in those behaviors.
(French et al., 2016)	UK	To explore young people’s views of and experiences with a mobile phone text-messaging intervention to promote safer-sex behavior.	Qualitative	20 adolescents (16 to 24 years)	Mobile phone interventions	The intervention increased knowledge, confidence, and safer-sex behaviors.
(Grandahl et al., 2016)	Sweden	To improve primary prevention of HPV by promoting vaccination and increased condom use among upper secondary schools.	RCT	741 adolescents (aged 16 years)	Sex education sessions (face-to-face structured interventions)	Face-to-face education delivery by health care providers, such as school nurses, is a highly feasible and effective way to increase adolescents’ beliefs and behavior toward primary prevention of HPV, regardless of socioeconomic status, ethnicity, or cultural background.
(Oliveira et al., 2016)	Brazil	To analyze the limits and the potentialities of the Papo Reto game, for construction of knowledge in the field of sexuality with adolescents.	Qualitative	23 adolescents (15 to 18 years)	Combined interventions (virtual game, workshops)	The game can be used as a pedagogic device for dealing with the subject of sexuality in adolescents. The results confirmed the potentiality of the contents for dealing with the complexity of reality from the point of view of gender.
(Rani et al., 2016)	India	To compare the knowledge and attitude regarding pubertal changes among pre-adolescent girls before and after the pubertal preparedness program	Quasi- experimental	104 pre- adolescent (12–14 years)	Sex education sessions	Pubertal preparedness programs and FAQs reinforcement sessions are effective in enhancing knowledge and developing a favorable attitude among pre-adolescent girls.
(Aventin et al., 2015)	Ireland	To design, develop, and optimize an educational intervention about young men and unintended teenage pregnancy based around an interactive film.	Mixed methods	360 adolescents (14 to 17 years)	Combined interventions: interactive film-based interventions (If I were Jack) with group discussion	The model of intervention reported in this paper was presented not as an ideal, but as an exemplar that other researchers might utilize, modify, and improve.
(Enah et al., 2015)	USA	To assess the acceptability and relevance of a web-based HIV prevention game for African American rural adolescents.	Mixed methods	42 adolescents (12 to 16 years)	Online interventions (game: Fast Car)	Using games for HIV prevention was found to be appealing and acceptable, but it was not found to be the best approach to HIV prevention with the target population.
(Hatami et al., 2015)	Iran	To evaluate the effect of organizing interactions using peer education in schools on the knowledge and attitude toward sexual health.	Quantitative	282 teenagers (14 to 18 years)	Peer education	The use of peer education in schools informally could enhance the knowledge and approach toward aspects of physical health, sexual behaviors, and social and mental changes among female adolescents.
(Jemmott et al., 2015)	2015 South Africa	To test the effect of an HIV/STI risk-reduction intervention.	RCT	1057 adolescents 9–18 years old	Sex education sessions	The HIV/STI risk-reduction intervention reduced unprotected intercourse and caused positive changes on theoretical constructs. Theory-based behavioral interventions with early adolescents can have long-lived effects in the context of a generalized severe HIV epidemic.
(Serowoky et al., 2015)	USA	To plan, implement, and evaluate a sustainable model of sexual health group programming (Cuídate) in a high school with a large Latino student population.	Quasi- experimental	24 adolescents (13 to 18 years)	Multiple interventional program (Cuídate)	The intervention showed significant increases in STI or HIV knowledge, self-efficacy, and intention to use condoms. It can be sustained in a school-based health center with results of efficacy.
(Elliott et al., 2013)	UK	To assess the effectiveness of the Scottish government’s National Sexual Health Demonstration Project (HR2).	Quasi- experimental	5283 pupils aged 15–16 years	Sex education sessions	Combining sex education and sexual health services has a limited impact on young people’s sexual health.
(Moodi et al., 2013)	Iran	To evaluate the effect of an educational program for puberty health on improving intermediate and high school female students’ knowledge in Birjand, Iran.	Quasi- experimental	302 female students (mean age 12.9)	Sex education sessions	Performing educational programs during puberty has a crucial role in young girls’ knowledge increase.
(Okanlawon and Asuzu, 2013)	Nigeria	To involve adolescents in school-based health-promotion activities that would improve their perception of risk in sexual behavior.	Quasi- experimental	519 adolescents	Peer education	Adolescents’ active participation in health-promotion activities should be encouraged, as it improves the perception of risk in sexual behavior among adolescents.
(Valli and Cogo, 2013)	Brazil	To analyze the structure of school blogs on sexuality and their utilization by adolescents.	Quantitative	11 blogs about sexuality	Online interventions (blog)	The blog is a virtual interaction tool common among adolescents that allows the adolescent to establish relationships with other teens interested in the topic, decreasing feelings of doubt, isolation, and shyness.
(Cornelius et al., 2012)	USA	To understand adolescents’ perceptions of mobile cell phone text-messaging-enhanced and mobile cell phone-based HIV- prevention interventions.	Qualitative	11 teenagers (13 to 18 years)	Mobile phone interventions	The messages increased participants’ HIV awareness and knowledge.
(Denny et al., 2012)	New Zealand	To determine the association between availability and quality of school health services and reproductive health outcomes among sexually active students.	Quantitative	2745 adolescents (13 to 17 years)	Interventions delivered through SBHCs	Health services may be able to lower the incidence of pregnancy by providing access to comprehensive health services, including contraceptive care that is easily available and appropriate for the student population.
(Martyn et al., 2012)	USA	To explore the effects of an event history calendar approach on adolescent sexual risk communication and sexual activity.	Mixed methods	30 adolescents (15 to 19 years)	Event history calendar	School nurses could use the event history calendar approach to improve adolescent communication on sexual risks and tailoring of interventions.
(Madeni et al., 2011)	Tanzania	To evaluate a reproductive health awareness program for the improvement of reproductive health for unmarried adolescent girls and boys in urban Tanzania.	Quasi- experimental	305 adolescents (11 to 16 years)	Combined interventions (sex education sessions and group discussions)	The reproductive health program improved the students’ knowledge and behavior about sexuality and decision making after the program for both girls and boys. Their attitudes were not likely to change based on the educational intervention.
(Fonseca et al., 2010)	Brazil	To find the perception of adolescents on the sexual orientation actions in a public school and to identify the actions’ fragilities and potentials.	Qualitative	15 adolescents (15 to 17 years)	Group discussions	Participative methodology promotes a welcoming and productive work climate and provides larger involvement and learning.
(Freitas and Dias, 2010)	Brazil	To understand teenagers’ perceptions about the development of their sexuality.	Qualitative	12 teenagers (11 to 19 years)	Workshops	Teenagers’ perceptions about their sexuality emerged from the debates and shared knowledge during the workshops.
(Levandowski and Schmidt, 2010)	Brazil	To enable the exchange of experiences and reflection about sexuality-related actions and choices.	Qualitative	270 adolescents (12 to 15 years)	Workshops	The intervention reduced psychosocial risk factors, providing a healthy development.
(Villarruel et al., 2010)	Mexico	To examine the effectiveness of a safer-sex program (Cuídate) on sexual behavior, use of condoms, and use of other contraceptives among Mexican youth 48 months after the intervention.	RCT	708 adolescents (mean age 19.22)	Multiple interventional program (Cuídate)	Results demonstrated the efficacy of Cuídate among Mexican adolescents. Future research, policy, and practice efforts should be directed at sustaining safe-sex practices across adolescents’ developmental and relationship trajectories.
(Camargo and Ferrari, 2009)	Brazil	To analyze the knowledge of adolescents on sexuality, contraceptive methods, pregnancy, and STDs/AIDS before and after prevention workshops.	Qualitative	117 adolescents (14 to 16 years)	Workshops	There is a need for systematic work, in the medium and long term, in schools regarding adolescent sexuality, as there was no increase in knowledge about STD transmission methods.
(Gubert et al., 2009)	Brazil	To address the use of educational technology as a strategy for health education among the teenagers in the school.	Qualitative	30 teenagers (14 to 18 years)	Workshops	Nursing professionals should produce/ readjust new technologies that support the educational process in health education, valuing the skills and aspirations of adolescents, going beyond traditional health education activities based on specific actions and that do not recognize the real needs.
(Beserra et al., 2008)	Brazil	To investigate the adolescents’ sexuality from the educative action of a nurse in the prevention of STDs.	Qualitative	10 adolescents (14 to 16 years)	Group discussions	The intervention allowed adolescents to explore and discuss many subjects that involved their sexuality, and it was also a moment to take actions on health education with the objective to prevent risks.
(Gallegos et al., 2008)	Mexico	To test the efficacy of a behavioral intervention designed to decrease risk of sexual behaviors for HIV/AIDS and unplanned pregnancies in Mexican adolescents.	RCT	832 adolescents, age 14–17	Combined interventions: sex education sessions and interactive games	The behavioral intervention represented an important effort, and was effective in promoting safe sexual behaviors among Mexican adolescents.
(Soares et al., 2008)	Brazil	To understand how adolescents live and exercise their sexuality.	Qualitative	350 adolescents (15 to 19 years)	Workshops	The workshops favored the discussion of attitude changes in the adolescents through the information, reflection, and expression of ideas and feelings, representing a process to be complemented by the family, school, and local social politics.
(Henderson et al., 2007)	Scotland	To assess the impact of a theoretically based sex education program (SHARE) delivered by teachers compared with conventional education in terms of conceptions and terminations registered by the NHS.	RCT	4196 female (mean age 20)	Multiple intervention program (SHARE)	Enhanced teacher-led school sex education (SHARE) improved knowledge and reduced regret, but did not reduce conceptions or terminations compared with conventional sex education.
(Tucker et al., 2007)	2006 UK-Lothian	To test for improved outcomes for the new Lothian Healthy Respect’s SHARE on teenage sexual behavior outcomes in the Lothian region.	Quasi- experimental	4381 secondary school pupils (average age 14.6 years)	Multiple intervention program (SHARE)	The findings demonstrated limited impact on sexual health behavior outcomes and raised questions about the likely and achievable sexual health gains for teenagers from school-based interventions.
(Amaral and Fonseca, 2006)	Brazil	To understand adolescents’ social representations on sexual initiation concerning gender.	Qualitative	16 adolescents (11 to 16 years)	Workshops	The strategy allowed the understanding of the social representations of teenagers about sexual initiation, being of great importance for planning the work developed with teenagers, supporting debates and reflections on the experience of healthy and responsible sexuality by young people.
(Beserra et al., 2006)	Brazil	To describe an experience to promote health and prevent STDs among teenagers.	Qualitative	28 adolescents (13 to 16 years)	Workshops	The strategy was effective at promoting teenagers’ adoption of preventative measures.
(Villarruel et al., 2006)	USA	To test the efficacy of a prevention intervention to reduce sexual risk behavior among Latino adolescents.	RCT	553 adolescents, aged 13 to 18 years	Multiple interventional program (Cuídate)	Results provided evidence for efficacy for HIV prevention in decreasing sexual activity and increasing condom use among Latino adolescents.
(Walker et al., 2006)	Mexico	To assess effects on condom use and other sexual behavior of an HIV prevention program at school that promotes the use of condoms with and without emergency contraception.	RCT	First-year high school students (n = 10954) (16–17 years)	Sex education sessions	A rigorously designed, implemented, and evaluated HIV education course based in public high schools did not reduce risk behavior, so such courses need to be redesigned and evaluated.
(Carvalho et al., 2005)	Brazil	To determine how the intervention in sexual guidance was experienced by adolescents.	Qualitative	13 adolescents (13 to 15 years)	Workshops	The analysis demonstrated a reconstruction /redefinition of meaning for the ideas related to sexuality, to gender, and to the wider social context.
(Barnes et al., 2004)	Australia	To evaluate the impact of changes in the health system and services on the roles and responsibilities of child health nurses and to identify professional development needs.	Qualitative	10 nurses	Combined interventions: health education and health information displays.	The school-based youth health nurse program provides nurses with a new, challenging, autonomous role within the school environment, and the opportunity to expand their role to incorporate all aspects of the health-promoting schools’ framework.
(Stephenson et al., 2004)	UK	To examine the effectiveness of one form of peer-led sex education.	RCT	8000 students (13 to 14 years)	Peer education	Peer-led sex education was effective in some ways, but broader strategies are needed to improve young people’s sexual health. The role of single-sex sessions should be further investigated.
(Lonczak et al., 2002)	USA	To examine the long-term effects of the full SSDP intervention on sexual behavior and associated outcomes assessed at age 21 years.	Non- randomized controlled trial	349 former fifth-grade students (aged 21 years)	Multiple interventional program (SSDP)	A theory-based social development program that promotes academic success, social competence, and bonding to school during the elementary grades can prevent risky sexual practices and adverse health consequences in early adulthood.
(Wight et al., 2002)	Scotland	To determine whether a theoretically based sex education program for adolescents (SHARE) delivered by teachers reduced unsafe sexual intercourse compared with current practice.	RCT	8430 pupils aged 13–15 years	Multiple intervention program (SHARE)	Compared with conventional sex education, this specially designed intervention did not reduce sexual risk-taking in adolescents.
(Lieberman et al., 2000)	USA	To assess the impact of an abstinence-based model for sexual education.	Quantitative	312 students (mean age 12.9)	Multiple intervention program (IMPPACT)	A small-group abstinence-based intervention can have some impact on adolescents’ attitudes and relationships (particularly with their parents).
(Dunn et al., 1998)	Canada	To evaluate a school-based HIV prevention intervention in adolescents.	Quasi- experimental	160 adolescents (14 to 15 years)	Sex education sessions	School-based interventions can improve adolescents’ short-term HIV/AIDS prevention knowledge, attitudes, self-efficacy, and behavioral intentions.
(Jemmott III et al., 1998)	USA	To evaluate the effects of abstinence and safer-sex HIV risk-reduction interventions on young inner-city African American adolescent’s HIV sexual risk behaviors when implemented by adult facilitators as compared with peer cofacilitators.	RCT	659 adolescents (mean age 11.8)	Sex education sessions	Both abstinence and safer-sex interventions can reduce HIV sexual risk behaviors, but safer-sex interventions may have longer-lasting effects, and may be especially effective with sexually experienced adolescents.
(Siegel et al., 1998)	USA	To determine the short-term effect of a middle and high school–based AIDS and sexuality intervention (RAPP) on knowledge, self-efficacy, and behavior intention.	Non- randomized controlled trial	Middle and high school students (n = 3635)	Multiple interventional program (RAPP): games, role playing, take-home exercises	At short-term follow-up, the RAPP intervention had a powerful effect on knowledge for all students and a moderate effect on sexual self-efficacy and safe behavior intention, particularly for high school students.
(Stephenson et al., 2008)	UK	To assess the long-term effects of a peer-led sex education program.	RCT	9000 students (13–14 years)	Peer education	Compared with conventional school sex education at age 13–14 y, this form of peer-led sex education was not associated with a change in teenage abortions, but may have led to fewer teenage births, and was popular with pupils. It merits consideration within broader teenage-pregnancy- prevention strategies.