This review aims to systematically gather and synthesize the current evidence on sexual health promotion interventions in order to assess the evidenced effects of sexual health promotion programs conducted in schools and targeting adolescents in Europe.

Databases were systematically searched using tailored search strategies in April 2022. The following electronic databases were searched: PubMed, CINAHL, ERIC, Education Research Complete, Web of Science, Scopus, and PsycINFO. The terms used in the search strategy can be categorized into population terms (e.g., adolescents, students), geographic terms (e.g., Europe), context terms (e.g., school), program terms (e.g., intervention, action study), and finally outcome terms (e.g., sexual health, sexual well-being, sexual health promotion). Boolean operators and MeSH terms were used as appropriate in the different databases. In addition to the database searches, the reference lists of the included articles and previous review studies were hand-searched with similar inclusion criteria as for this study. See Supplementary file 1 for further details on the applied search strategies.

Studies that met the following inclusion criteria were considered eligible: (a) published between 2012 and 2022; (b) conducted in a European country/countries; (c) targeting adolescents (age 12–19); (d) carried out in high school and upper secondary school/vocational school by teachers, health professionals or non-governmental organizations (e) reported on at least one outcome connected to sexual health-promotion and/or positive aspects regarding sexual health. Study designs excluded from this review were cross-sectional-, case, and review studies. Likewise, book chapters, theses, and studies that were not written in English were also excluded. Moreover, studies applying a risk perspective and/or only measuring the risk aspects of sexual health (e.g., knowledge about STIs, and unplanned pregnancy) were excluded. Studies that focused on a specific group of adolescents not representative of the general population (e.g., special education classes) were also excluded.

Article eligibility was initially assessed by one reviewer (RA), who screened the titles and abstracts to exclude duplicates and obviously irrelevant studies. Full texts were read when abstracts met inclusion criteria and when abstract information was insufficient in order to determine eligibility. A second reviewer (JN) assessed the potential eligibility of all the records. Disagreements between reviewers regarding study inclusion were resolved by discussion with reviewers AKF and KG. See the PRISMA flow chart (Figure 1) for detailed information regarding the identification, screening, and record selection process. Initially, 10,897 records were identified, and when duplicates were removed, 8,065 records remained for screening. When titles and abstracts had been screened, 174 records remained for full-text assessment, which after appraisal, led to a list of 45 studies that were assessed and discussed together with the other reviewers (JN, KG, AKF). Studies considered solely to apply a risk perspective were excluded after critical discussions. Thus, finally, 17 records were included in the review, reporting on 16 individual studies. Information from the included records was systematically extracted into a matrix (Supplementary file 2) according to a predetermined protocol to summarize and analyze relevant characteristics. Parallel data extraction was conducted by a second reviewer (JN).

Data coding was performed according to a protocol and included study characteristics (e.g., aim, study design), intervention content (e.g., focus and duration), study methods (e.g., sample,), outcomes relevant to the current review (e.g., sexual attitudes, sexual self-esteem) as well as study results. For studies with a quantitative research design, statistical values from the analyses of the intervention effect were extracted from the final point of measurement (e.g., final follow-up measurement). A narrative synthesis of the included studies was performed, highlighting the collective results. See Supplementary file 2 for the extracted data and key information of the included studies.

The risk of bias of the included intervention studies in relation to study design, conduct, and analysis was assessed and rated according to principles for critical appraisal developed by JBI (44), as well as the corresponding risk of bias checklists developed by the National Institute for Health and Care Excellence, NICE (45, 46). The critical appraisal instruments have been developed to account for variations in research designs and applied methods among studies included in systematic reviews. Moreover, in accordance with the NICE guidelines, each study was awarded a quality grading (++, +, −), which represents the quality as well as the validity of each study included. Studies with all or most checklist criteria fulfilled, indicating overall high quality and a low risk of bias were graded ++, studies with most or some of the checklist criteria fulfilled were graded with a single plus (+), and finally, studies with a high risk of bias and conclusions that are likely to alter were graded with a minus (−). The quality score for each study can be viewed in Supplementary file 2.

Three of the studies had a qualitative research design: Helbekkmo et al. (47), Hirvonen et al. (48), and van Lieshout et al. (49), while 13 of the studies had a quantitative research design (50–62). Three of the quantitative studies were randomized controlled trials: Escribano et al. (50), Pakarinen et al. (51), and Ponsford et al. (52), two applied cluster-randomized controlled designs: de Lijster et al. (53) and Espada et al. (60), and four applied a quasi-experimental design: Elliot et al. (54), García-Vázquez et al. (55), Zmyj and Wehlig (61), and Peters et al. (62). Finally, four studies applied a descriptive design only reporting on post-intervention results: Alekseeva et al. (56), Başar et al. (57), Heras et al. (58), and Pakarinen et al. (59).

The studies included are conducted in different parts of Europe. Four studies were conducted in Southern Europe [Spain (48, 49, 53, 57)], seven in Western Europe [the Netherlands (51, 55, 56); Germany (57); the United Kingdom (47, 51, 54)], three in Northern Europe [Finland (50, 61); Norway (46)], and finally two studies were conducted in Eastern Europe [Turkey (59); Russia (58)]. The age of the participants in the studies ranged from 11 to 19 years [the age range in the study by (56) was 13–23, but age 23 represented the participants’ age at final follow-up]. Most studies were conducted in high schools/secondary schools (47–50, 52–55, 57, 58, 60–62), and only two studies were conducted in vocational schools (51, 59). In one study, the intervention was conducted in both high school and upper secondary schools/vocational schools (56).

Alekseeva et al. (56) focused on taboos and stigma as well as the prevention and promotion of sexual health and rights, and a healthy lifestyle. The intervention Dance4life was conducted in four different cities in Russia, targeting adolescents between 13 and 19 years old, and encompassed four consecutive stages. No further information on how long the intervention lasted was given. Başar et al. (57), like Alekseeva et al. (56), focused on reproductive health and rights, however, the program also centered around the adolescent period, physiology, reproductive system anatomy, and prevention of STI:s. The study by Başar et al. (57) was conducted in a secondary school in Turkey, with adolescents between 11 and 14 years as the target group. The intervention lasted for a total of 14 h, and separate sessions were arranged for girls and boys during the whole intervention.

Peters et al. (62) reported on an intervention called “Multiple Choice 4 U” in the Netherlands that targeted adolescents in grade 7 (median age 13.5 years). The intervention took place in classrooms during 10 lessons and focused on three psychosocial and behavioral determinants: outcome expectancies (e.g., short-term physical and social consequences), social influences (e.g., social norms), and self-efficacy (e.g., negotiation skills). The Benzies & Batchies intervention, studied by de Lijster et al. (53), was also conducted in the Netherlands, but within vocational and secondary schools with adolescents between 12 and 16 as the target group. The focus of the Benzies & Batchies intervention was to prevent sexual harassment by focusing on skills and resilience training regarding social and sexual behavior. The intervention consisted of 3×100 min lessons, 30 min play, and 60 min discussion, as well as introductory and closing lessons. In another study (54), the intervention likewise focused on sexual health skills training in an intervention called Healthy Respect 2 (HR2). Along with skills training, the program additionally focused on knowledge and attitudes. The intervention was conducted in 12 high schools in Scotland by specially trained teachers, and the average number of delivered sessions was 22. Adolescents participating in this study were aged 15–16 years old. Hirvonen et al. (48) evaluated the STASH-intervention, which was also set in the United Kingdom. The intervention lasted 10 weeks and focused on online peer support (sharing sexual health messages on Facebook) among adolescents aged 14–16 years old.

Escribano et al. (50) examined the effect of the COMPAS-intervention conducted in high schools in Spain among students aged 14–16 years. The focus of the intervention was sexual health promotion as well as HIV prevention. The intervention content covered five components: information, social skills, training, problem-solving skills, and strategies to maintain safer sexual behaviors. Another study, Espada et al. (60), also evaluated the COMPAS-intervention in Spain, comparing it to the ¡Cuı ́date-intervention, which has a similar focus as COMPAS, but with a specific session on communication and negotiation skills. The interventions were conducted in 18 public high schools in Spain. The intensity of the interventions was quite similar, as the COMPAS-intervention consisted of five 50 min sessions and the ¡Cuı ́date-intervention consisted of six 45 min sessions. Furthermore, García-Vázquez et al. (55) also conducted their intervention study in Spain. The intervention, “Neither Ogres nor Princesses” (NONP), aimed to promote sexual rights and respect for others and to generate conditions for adolescents to make autonomous responsible decisions regarding sexual health and rights. The intervention was delivered by teachers over 4 years with a total of 20.7 h of sex education as well as 7.5 h of workshops.

Helbekkmo et al. (47) evaluated Norwegian students’ experience with the «Week 6» program. The program targeted 15- and 16-year-old adolescents, and the focus of the program was positive sexuality. The program lasted 1 week and focused on different learning goals regarding sexuality according to the school curriculum. Another study, Heras et al. (58), likewise focused on the positive aspects of sexuality and sexual health by highlighting and supporting students’ development of skills needed to maintain a healthy lifestyle and well-being through the SOMOS-intervention. The study was conducted in Spain and consisted of eight sessions that lasted between 12 and 50 min. The target group in the study was 13–19-year-olds.

In the study by Pakarinen et al. (51) the intervention focused on Finnish adolescents’ attitudes, knowledge, and sexual behavior. The intervention targeted adolescents aged 15–19 years and lasted 11 weeks. Another study conducted in Finland by Pakarinen et al. (59) evaluated the same intervention. Thus, the intervention duration and focus were the same as in Pakarinen et al. (51). However, the target group in Pakarinen et al. (59) was first-year students in vocational schools aged 15–16 years old, and the study focused on the participants’ self-evaluation and experiences of the intervention. Moreover, the study by Ponsford et al. (52), like Pakarinen et al. (51), analyzed students’ experiences of and preferences regarding sex education and evaluated the Positive Choices program. The focus of the intervention was knowledge, attitudes, and skills. The intervention was conducted in secondary schools in the United Kingdom (participants aged 13–14 years) for one academic year.

Van Lieshout et al. (49) evaluated the Long Live Love + (LLL+) intervention in the Netherlands. The intervention target group was adolescents aged 15–17 years, and the focus was on four different themes: relationships, (un)safe sex and contraception, (un)safe sex and STIs, and sexual diversity, with a duration of two 45-min sessions per theme. Similarly to Van Lieshout et al. (49), the study by Zmyj and Wehling (61) encompassed the topic of sexual diversity, more specifically homonegativity. The workshop was part of the school curriculum in a high school in Germany, and the focus was on changing attitudes toward LGBT-people by encouraging acceptance and respect. The workshop lasted 4 h, and the target group was adolescents aged 14–16 years old.

In the narrative synthesis of the studies, five focus areas of the interventions were identified, reflecting both intervention content and related outcomes: (i) attitudes toward sexual health (50, 51, 53, 55, 58, 60, 62), (ii) sexual health awareness (54, 55, 57, 62), (iii) skills related to sexual health (50, 51, 53, 55, 62), (iv) norm perception in relation to sexuality and sexual health (50, 51, 53, 54, 61) and (v) students’ perception of the intervention program (47–49, 52, 56, 59). The attitudes category includes attitudes toward sexual health in general, as well as attitudes toward safe sex, condom use, media influence, and masturbation. The awareness category represents knowledge, awareness, and information on sexual health outcomes. The third category, skills, covers general self-efficacy, self-efficacy in condom use, self-efficacy in communication as well as sexual self-esteem. The fourth category contains outcomes connected to norm perception in relation to sexuality and sexual health, e.g., feelings of social acceptance, acceptability of same-sex relationships, perceived norm, as well as attitudes toward gender roles. The last category highlights students’ perception of the program (e.g., students’ perception of content, implementation of the intervention, and their learning progress). See Table 1 for an overview of the included studies and the categorization of outcomes.

Ten of the studies with a quantitative design included in this review showed evidence of effect (50–59). The results of the study by Alekseeva et al. (56) showed that 100% of the respondents had improved their knowledge of sexual reproductive health and rights (SRHR) at the post-intervention measurement, 89% reported improved knowledge on how to communicate about sex and sexuality, and 87% had learned to discuss sensitive issues. Moreover, the results showed perceived improvements in skills. The respondents reported greater responsibility for their actions and choices and improvements in communication. Finally, the results indicated an increase in legal literacy related to sexual health among the respondents. The study by Başar et al. (57) showed statistically significant effects on sexual health knowledge for the intervention group at the follow-up, 2 months after the intervention had ended, and there was a statistically significant difference between comparisons between intervention and control group. Furthermore, the results of the study by de Lijster et al. (53) showed a significant improvement in sexual self-esteem for the intervention group.

In the study by Elliot et al. (54), several statistically significant changes were found, showing both positive and negative effects. There was a significant increase in sexual health knowledge for both boys and girls. Group and time interaction was also significant regarding sexual health knowledge, although for girls only. Moreover, there was a significant increase in the intention to use condoms for boys in the intervention group (but not for girls). There was furthermore a statistically significant increase regarding the acceptability to use condoms, although it should be noted that in this specific case, the numerical increase indicates an actual negative development in the acceptability of condom use, showing that girls in the intervention group became less acceptable of condom use. No significant changes were found in the follow-up measurement for boys regarding this outcome, nor was any improvement regarding the acceptability of same-sex relationships found.

In the study by Escribano et al. (50), there were statistically significant positive changes in attitudes toward condom use, attitudes toward condom use when barriers exist, and self-efficacy for the intervention group at the follow-up measurement. Furthermore, the intervention group in the study by García-Vázquez et al. (55) showed significant improvement in sexual health knowledge as well as in skills, but there was only a significant difference at the first post-test measurement regarding the latter outcome. In addition to these studies, Heras et al. (58) showed that there was a statistically significant increase in positive attitudes toward sexual health in general for the intervention group, although with a small effect size, as well as a significant drop in negative attitudes toward masturbation, with a moderate size effect. There was no follow-up measurement, only a post-test measurement in this study. In the study by Pakarinen et al. (51), a statistically significant effect was found for total attitudes, however, the effect concerns differences in mean scores between baseline and post-test and also between post-test and follow-up. The mean baseline and follow-up scores were identical, which means that the results of this study should be interpreted with caution. Regarding the sub-dimensions of total attitudes, no significant effects were found for self-efficacy in condom use. Statistically significant effects were found for social acceptance of condom use and self-efficacy in communication. A small decrease in these outcomes was found from baseline to follow-up. No statistically significant effects or differences were found for the control group.

Pakarinen et al. (59) aimed to examine students’ self-evaluations of a sexual health promotion intervention. Most of the students agreed with the following statements regarding the implementation of the lessons: the content of the lessons was easy to understand (62% agreed), and there was a possibility to ask questions during lessons (53.7% agreed). Finally, Ponsford et al. (52) assessed the feasibility and acceptability of the Positive Choices-intervention, and according to the intervention group, the program covers most of the positive sexual health topics quite well. The topics of sexual consent (IG 82.9%; agreed; CG 62.2% agreed), masturbation (IG 47.4% agreed; CG 15% agreed), love (IG 49.4% agreed; CG 24.7% agreed), sexual pleasure (IG 60.1% agreed; CG 24.7% agreed), readiness for intimacy (IG 41.6% agreed; CG 20.6% agreed), and sexual rights (IG 53.9% agreed; CG 25.8% agreed) are considered to be covered to a higher degree in the intervention group when compared to the control group. Three quantitative studies did not report any statistically significant intervention effects on any of the outcomes of interest in this review (6, 13, 16).

The three studies with a qualitative design—Helbekkmo et al. (47), Hirvonen et al. (48), and van Lieshout et al. (49)—all showed good evidence of effect. The overall theme of the qualitative content analysis in the study by Helbekkmo et al. (47) was that the students “liked «Week 6» but had expected more about sex in the sex week.” Subthemes indicate that the students wanted to learn about realistic and relevant subjects as well as to be able to contribute to the content and implementation of the program. Categories that emerged in analyses were (i) organization and content, (ii) positive experiences (iii) potential for improvement, (iv) learning outcome. Hirvonen et al. (48) investigated opportunities and challenges with peer-to-peer sexual health education through social media messages. A total of 35% of the participants were happy to be part of the social media groups and take part of the messages. Among peer supporters, the training helped sensitize them to web-based sexual health content more generally. Messages with humor content, brief, clear texts, memes, and pictures, as well as bold colors, were appreciated by the participants. The participants rarely commented on the posts in general. Some students expressed disinterest in the STASH posts or looked at them out of boredom, and others responded with openness and interest. Finally, pupils in the study by van Lieshout et al. (49) showed more knowledge on contraceptives, and confidence in discussing condoms. Furthermore, participants showed more positive attitudes and confidence in testing and more knowledge of STIs overall. Finally, participants showed more understanding of diversity among LGBT persons and empathy toward persons identifying as LGBT.

This review synthesizes findings from quantitative as well as qualitative original studies. Thus, there is a variation in both study and intervention design in the included studies providing a more nuanced and holistic overview of the evidence base. Relevant records were systematically searched for in seven scientific databases. The quality of the records included was evaluated according to the NICE checklist, and the recommendations by JBI were followed. Most of the included studies were deemed to display a low risk of bias, and the conclusions of the review are therefore unlikely to alter (only one study (56), was considered to display a high risk of bias). However, some limitations to this study should be considered when interpreting the results. First, there is a risk that relevant research published in languages other than English was overlooked and excluded. Europe, when compared to, e.g., the USA, is very diverse in languages. Thus, the fact that only articles written in English were included in this review study might also be a possible reason for the lack of diversity in the countries included. Second, gray literature could have been searched in order to find additional articles. Nonetheless, searching for gray literature poses a challenge in relation to systematicity and replicability. Third, there were challenges related to determining the health intervention approach (i.e., risk approach or health-resource approach) for the studies in the study selection process. Studies that were considered to solely apply a risk perspective were excluded in order to align with the review aim. However, after several critical discussions, studies encompassing positive sexual health outcomes but applying a mixed prevention and promotion intervention approach were included in the data synthesized. Another important limitation to consider when interpreting the results is that the data this review is based on did not allow for a statistical meta-analysis of the intervention effects, which would have provided more robust statistical calculations on the pooled effectiveness in addition to the narrative evidence synthesis.

The evidence synthesis provides an overview of holistic and resource-focused sexual health interventions conducted in European schools, reflecting an emerging sexual health promotion approach that goes beyond the prevention of STIs and unplanned pregnancies – and instead highlights the importance of equality, respect, communication skills, attitudes toward sexual health and other positive and strengthening sexual health resources. The majority of the included studies showed evidence of statistically significant effects on at least one of the health promotion outcomes of interest, and a few studies even showed positive effects on multiple outcomes and can therefore be considered good examples of sexual health promotion interventions. The study also contributes with an overview of the intervention and outcome focus areas in the sexual health promotion interventions in Europe. The existing programs cover attitudes toward sexual health and students’ perception of the program well. However, there is a lack of attentive focus on the comprehensive, multi-dimensional sexual health literacy concept, despite its importance for positive sexual health development for adolescents. Thus it can be recommended to be studied further and included in future intervention studies.