***TASK*** the task is to summarize an input biomedical literature in six sentences 
    ***INPUT*** the input is a biomedical literature 
    ***OUTPUT*** the output is the summary of an input biomedical literature in six sentences 
    ***DOCUMENTATION*** 
    ***EXAMPLES*** 
    Input: BACKGROUND Concerns about adverse consequences of early childbearing and risk of sexually transmitted diseases ( STD ) have renewed interest in the sexual behaviour of adolescents in developing countries , where they represent a large proportion of the population and are at highest risk . To date , little is known about the sexual knowledge of adolescents in developing countries . This study 's primary objective was to evaluate the effectiveness of a responsible sexuality education programme ( RSP ) in changing knowledge associated with sex and sexuality ; secondary objectives were to evaluate changes in attitudes and behavioural intent . METHODS A cluster r and omized design r and omizing high school classes in Belize City . Subjects were 13 - 19 years old . RESULTS Seven schools in Belize City were selected ; 8 classrooms were r and omized to the intervention arm and 11 classrooms to the control arm ( N = 399 ) . The intervention was associated with two more correct answers on the post-test ( difference score was 2.22 points , 95 % CI = 0.53 , 3.91 ) after adjusting for gender and previous sexual experience . After controlling for gender and previous sexual experience , the intervention was associated with no change in the attitudes ( 0.06 , 95 % CI : -2.89 , 2.82 ) or behavioural intent domains ( 0.84 , 95 % CI : -1.12 , 2.46 ) . CONCLUSIONS Greater changes in knowledge were observed in the intervention group than in the control group following the intervention . Changes were not observed for the attitude or behavioural intent domains . These results and the results of similar studies may be used to further improve sex education programmes as it is imperative that students have access to the information necessary to make informed decisions regarding their sexual health Objective To evaluate the effectiveness of youth development in reducing  teenage pregnancy , substance use , and other outcomes . Design Prospect i ve matched comparison study . Setting 54 youth service sites in Engl and . Participants Young people ( n=2724 ) aged 13 - 15 years at baseline deemed by professionals as at risk of teenage pregnancy , substance misuse , or school exclusion or to be vulnerable .  Intervention Intensive , multicomponent youth development programme including sex and drugs education ( Young People ’s Development Programme ) versus st and ard youth provision . Main outcome measures Various , including pregnancy , weekly cannabis use , and monthly drunkenness at 18 months . Results Young women in the intervention group more commonly reported pregnancy than did those in the comparison group ( 16 % v 6 % ; adjusted odds ratio 3.55 , 95 % confidence interval 1.32 to 9.50 ) . Young women in the intervention group also more commonly reported early heterosexual experience ( 58 % v 33 % ; adjusted odds ratio 2.53 , 1.09 to 5.92 ) and expectation of teenage parenthood ( 34 % v 24 % ; 1.61 , 1.07 to 2.43 ) . Conclusions No evidence was found that the intervention was effective in delaying heterosexual experience or reducing pregnancies , drunkenness , or cannabis use . Some results suggested an adverse effect . Although method ological limitations may at least partly explain these findings , any further implementation of such interventions in the UK should be only within r and omised trials OBJECTIVE To test the efficacy of a prevention intervention to reduce sexual risk behavior among Latino adolescents . DESIGN R and omized controlled trial from April 2000 through March 2003 , with data collection before and after intervention and at 3 , 6 , and 12 months . SETTING Northeast Philadelphia schools . PARTICIPANTS Latinos aged 13 through 18 years ( 249 males and 304 females ) ; 81.6 % retained at 12-month follow-up . INTERVENTIONS The HIV and health-promotion control interventions consisted of six 50-minute modules delivered by adult facilitators to small , mixed-gender groups  in English or Spanish . Main Outcome Measure Self-reported sexual behavior . RESULTS Analyses using generalized estimation equations over the follow-up period revealed that adolescents in the HIV intervention were less likely to report sexual intercourse ( odds ratio , 0.66 ; 95 % confidence interval [ CI ] , 0.46 - 0.96 ) , multiple partners ( odds ratio , 0.53 ; 95 % CI , 0.31 - 0.90 ) , and days of unprotected intercourse ( relative risk , 0.47 ; 95 % CI , 0.26 - 0.84 ) and more likely to report using condoms consistently ( odds ratio , 1.91 ; 95 % CI , 1.24 - 2.93 ) . Baseline sexual experience and language use moderated intervention efficacy . Adolescents assigned to the HIV intervention who were sexually inexperienced at baseline reported fewer days of unprotected sex ( relative risk , 0.22 ; 95 % CI , 0.08 - 0.63 ) ; Spanish speakers were more likely to have used a condom at last intercourse ( odds ratio , 4.73 ; 95 % CI , 1.72 - 12.97 ) and had a greater proportion of protected sex ( mean difference , 0.35 ; P<.01 ) compared with similar adolescents in the health-promotion intervention . CONCLUSION Results provide evidence for the efficacy of HIV intervention in decreasing sexual activity and increasing condom use among Latino adolescents Recent evidence suggests that conditional cash transfer programs for schooling are effective in raising school enrollment and attendance . However , there is also reason to believe that such programs can affect other outcomes , such as the sexual behavior of their young beneficiaries .  Zomba Cash Transfer Program is a r and omized , ongoing conditional cash transfer intervention targeting young women in Malawi that provides incentives ( in the form of school fees and cash transfers ) to current schoolgirls and recent dropouts to stay in or return to school . An average offer of US$ 10/month conditional on satisfactory school attendance – plus direct payment of secondary school fees – led to significant declines in early marriage , teenage pregnancy , and self-reported sexual activity among program beneficiaries after just one year of program implementation . For program beneficiaries who were out of school at baseline , the probability of getting married and becoming pregnant declined by more than 40 percent and 30 percent , respectively . In addition , the incidence of the onset of sexual activity was 38 percent lower among all program beneficiaries than the control group . Overall , these results suggest that conditional cash transfer programs not only serve as useful tools for improving school attendance , but may also reduce sexual activity , teen pregnancy , and early marriage Objective To assess the impact of a theoretically based sex education programme ( SHARE ) delivered by teachers compared with conventional education in terms of conceptions and terminations registered by the NHS . Design Follow-up of cluster r and omised trial 4.5 years after intervention . Setting NHS records of women who had attended 25 secondary schools in east Scotl and . Participants 4196 women ( 99.5 % of those eligible ) .  Intervention SHARE programme ( intervention group ) v existing sex education ( control group ) . Main outcome measure NHS recorded conceptions and terminations for the achieved sample linked at age 20 . Results In an “ intention to treat ” analysis there were no significant differences between the groups in registered conceptions per 1000 pupils ( 300 SHARE v 274 control ; difference 26 , 95 % confidence interval −33 to 86 ) and terminations per 1000 pupils ( 127 v 112 ; difference 15 , −13 to 42 ) between ages 16 and 20 . Conclusions This specially design ed sex education programme did not reduce conceptions or terminations by age 20 compared with conventional provision . The lack of effect was not due to quality of delivery . Enhancing teacher led school sex education beyond conventional provision in eastern Scotl and is unlikely to reduce terminations in teenagers . Trial registration IS RCT N48719575 CONTEXT Latino and black adolescents are disproportionately affected by STDs , including HIV , and unintended pregnancies . Few parent-based interventions have targeted these youth , focused on early adolescence and had high participation rates . METHODS Between 2003 and 2009 , a r and omized clinical trial was conducted with 2,016 Latino and black mother-adolescent dyads in New York City . Adolescents were eligible if they were in grade 6 or 7 . Dyads were assigned to one of three conditions : a parent-based intervention , Families Talking Together ( FTT ) ; an adolescent-only intervention , Making a Difference ! ( MAD ) ; or a combined FTT+MAD intervention . Respondents completed question naires at baseline and 12 months later . Single-degree-of-freedom contrasts and logistic regression analysis were used to evaluate differences in outcomes by intervention . RESULTS The proportion of youth who reported ever having engaged in vaginal intercourse increased over the study period by eight percentage points among those in the MAD group , five points in the FTT group and three points in the combined group ; the differences among these increases were not statistically significant . Adolescents in the two FTT groups were significantly more likely than those in the MAD group to indicate that their mother had talked to them about not having intercourse ( 79 % vs. 68 % ) . They also scored higher than youth in the MAD group on measures of communication and perceived maternal attributes , and lower on activities that might lead to risky behaviors . CONCLUSIONS The proportions of adolescents who initiated intercourse during the study period were not significantly different across groups , implying that the interventions were comparable . Findings suggest that FTT may have led to improved parenting behaviors IMPORTANCE Preventing early pregnancy among vulnerable adolescents requires innovative and sustained approaches . Prime Time , a youth development intervention , aims to reduce pregnancy risk among adolescent girls seeking clinic services who are at high risk for pregnancy . OBJECTIVE To evaluate sexual risk behaviors and related outcomes with a 24-month postbaseline survey , 6 months after the conclusion of the Prime Time intervention . DESIGN R and omized controlled trial . SETTING Community and school-based primary care clinics . PARTICIPANTS Of 253 sexually active 13- to 17-year-old girls meeting specified risk criteria , 236 ( 93.3 % ) completed the 24-month follow-up survey . INTERVENTION Offered during an 18-month period , Prime Time includes case management and youth leadership programs . MAIN OUTCOME MEASURES Self-reported consistency of condom , hormonal , and dual- method contraceptive use with most recent male sex partner and number of male sex partners in the past 6 months . RESULTS At 24-month follow-up , the intervention group reported significantly more consistent use of condoms , hormonal contraception , and dual- method contraception than the control group . Intervention participants also reported improvements in family connectedness and self-efficacy to refuse unwanted sex , and reductions in the perceived importance of having sex . No between-group differences were found in the number of recent male sex partners . CONCLUSIONS AND RELEVANCE This study contributes to what has been a dearth of evidence regarding youth development interventions offered through clinic setting s , where access to high-risk adolescents is plentiful but few efforts have emphasized a dual approach of strengthening sexual and nonsexual protective factors while addressing risk . Findings suggest that health services grounded in a youth development framework can lead to long-term reductions in sexual risk among vulnerable youth PURPOSE Prime Time , a youth development intervention , aims to reduce pregnancy risk among adolescent girls seeking clinic service who are at high risk for pregnancy . This article examines sexual risk behaviors and hypothesized psychosocial mediators after 12 months of the Prime Time intervention . METHODS This study was a r and omized controlled trial with 253 girls aged 13 - 17 years meeting specified risk criteria . Intervention participants were involved in Prime Time programming plus usual clinic services for 18 months , control participants received usual clinic services . The intervention used a combination of case management and peer leadership programs . Participants in this interim outcomes study completed self-report surveys at baseline and 12 months after enrollment . Surveys assessed sexual risk behaviors and psychosocial factors targeted for change by Prime Time . RESULTS At the 12-month interim , the intervention group reported more consistent use of condoms , hormonal contraception , and dual contraceptive methods with their most recent partner as compared with the control group . The intervention group also reported greater stress management skills with trends toward higher levels of prosocial connectedness at school and with family . No between-group differences were noted in psychosocial measures specific to sex and contraceptive use . CONCLUSION Preventing early pregnancy among high-risk adolescents requires multifaceted , sustained approaches . An important research focus involves testing youth development interventions offered through clinic setting s , where access to high-risk adolescents is plentiful and few efforts have emphasized a dual approach of building protective factors while addressing risk . Findings suggest that youth development interventions through clinic setting s hold promise in reducing pregnancy risk among high-risk youth Abstract Objective : To determine whether a theoretically based sex education programme for adolescents ( SHARE ) delivered by teachers reduced unsafe sexual intercourse compared with current practice . Design : Cluster r and omised trial with follow up two years after baseline ( six months after intervention ) . A process evaluation investigated the delivery of sex education and broader features of each school . Setting : Twenty five secondary schools in east Scotl and . Participants : 8430 pupils aged 13 - 15 years ; 7616 completed the baseline question naire and 5854 completed the two year follow up question naire . Intervention : SHARE programme ( intervention group ) versus existing sex education ( control programme ) . Main outcome measures : Self reported exposure to sexually transmitted disease , use of condoms and contraceptives 
    Output:
    
However , this reduction was not statistically significant from cluster RCTs .
Evidence on the possible effects of interventions on secondary outcomes ( initiation of sexual intercourse , use of birth control methods , abortion , childbirth , sexually transmitted diseases ) was not conclusive .
Educational interventions Educational interventions were unlikely to significantly delay the initiation of sexual intercourse among adolescents compared to controls ( RR 0.95 , 95 % CI 0.71 to 1.27 ; 2 studies , 672 participants , low quality evidence ) .Educational interventions significantly increased reported condom use at last sex in adolescents compared to controls who did not receive the intervention ( RR 1.18 , 95 % CI 1.06 to 1.32 ; 2 studies , 1431 participants , moderate quality evidence ) .However , it is not clear if the educational interventions had any effect on unintended pregnancy as this was not reported by any of the included studies .
Contraceptive-promoting interventions For adolescents who received contraceptive-promoting interventions  , there was little or no difference in the risk of unintended first pregnancy compared to controls ( RR 1.01 , 95 % CI 0.81 to 1.26 ; 2 studies , 3,440 participants , moderate quality evidence ) .The use of hormonal contraceptives was significantly higher in adolescents in the intervention group compared to those in the control group ( RR 2.22 , 95 % CI 1.07 to 4.62 ; 2 studies , 3,091 participants , high quality evidence ) AUTHORS ' CONCLUSIONS A combination of educational and contraceptive-promoting interventions appears to reduce unintended pregnancy among adolescents .
Evidence for programme effects on biological measures is limited .
The variability in study population s , interventions and outcomes of included trials , and the paucity of studies directly comparing different interventions preclude a definitive conclusion regarding which type of intervention is most effective