Intervention Now to Eliminate Repeat Unintended Pregnancy in Teenagers (INTERUPT): a systematic review of intervention effectiveness and cost-effectiveness, and qualitative and realist synthesis of implementation factors and user engagement.

BACKGROUND The UK has one of the highest rates of teenage pregnancies in Western Europe. One-fifth of these are repeat pregnancies. Unintended conceptions can cause substantial emotional, psychological and educational harm to teenagers, often with enduring implications for life chances. Babies of teenage mothers have increased mortality and are at a significantly increased risk of poverty, educational underachievement and unemployment later in life, with associated costs to society. It is important to identify effective, cost-effective and acceptable interventions. OBJECTIVES To identify who is at the greatest risk of repeat unintended pregnancies; which interventions are effective and cost-effective; and what the barriers to and facilitators of the uptake of these interventions are. DATA SOURCES We conducted a multistreamed, mixed-methods systematic review informed by service user and provider consultation to examine worldwide peer-reviewed evidence and UK-generated grey literature to find and evaluate interventions to reduce repeat unintended teenage pregnancies. We searched the following electronic databases: MEDLINE and MEDLINE In-Process & Other Non-Indexed Citations, PsycINFO, Cumulative Index to Nursing and Allied Health Literature, The Cochrane Library (Cochrane Database of Systematic Reviews, Database of Abstracts of Reviews of Effects and the Health Technology Assessment Database), EMBASE (Excerpta Medica database), British Nursing Index, Educational Resources Information Center, Sociological Abstracts, Applied Social Sciences Index and Abstracts, BiblioMap (the Evidence for Policy and Practice Information and Co-ordinating Centre register of health promotion and public health research), Social Sciences Citation Index (supported by Web of Knowledge), Research Papers in Economics, EconLit (American Economic Association's electronic bibliography), OpenGrey, Scopus, Scirus, Social Care Online, National Research Register, National Institute for Health Research Clinical Research Network Portfolio and Index to THESES. Searches were conducted in May 2013 and updated in June 2014. In addition, we conducted a systematic search of Google (Google Inc., Mountain View, CA, USA) in January 2014. Database searches were guided by an advisory group of stakeholders. REVIEW METHODS To address the topic's complexities, we used a structured, innovative and iterative approach combining methods tailored to each evidence stream. Quantitative data (effectiveness, cost-effectiveness, risk factors and effect modifiers) were synthesised with reference to Cochrane guidelines for evaluating evidence on public health interventions. Qualitative evidence addressing facilitators of and barriers to the uptake of interventions, experience and acceptability of interventions was synthesised thematically. We applied the principles of realist synthesis to uncover theories and mechanisms underpinning interventions (what works, for whom and in what context). Finally, we conducted an overarching narrative of synthesis of evidence and gathered service user feedback. RESULTS We identified 8664 documents initially, and 816 in repeat searches. We filtered these to 12 randomised controlled trials (RCTs), four quasi-RCTs, 10 qualitative studies and 53 other quantitative studies published between 1996 and 2012. None of the RCTs was based in the UK. The RCTs evaluated an emergency contraception programme and psychosocial interventions. We found no evidence for effectiveness with regard to condom use, contraceptive use or rates of unprotected sex or use of birth control. Our primary outcome was repeat conception rate: the event rate was 132 of 308 (43%) in the intervention group versus 140 of 289 (48%) for the control goup, with a non-significant risk ratio (RR) of 0.92 [95% confidence interval (CI) 0.78 to 1.08]. Four studies reported subsequent birth rates: 29 of 237 (12%) events for the intervention arm versus 46 out of 224 (21%) for the control arm, with a RR of 0.60 (95% CI 0.39 to 0.93). Many repeat conceptions occurred in the context of poverty, low expectations and aspirations, and negligible opportunities. Service user feedback suggested that there were specific motivations for many repeat conceptions, for example to replace loss or to please a partner. Realist synthesis highlighted that context, motivation, planning for the future and letting young women take control with connectedness and tailoring provide a conceptual framework for future research. LIMITATIONS Included studies rarely characterised adolescent pregnancy as intended or unintended, that is interventions to reduce repeat conceptions rarely addressed whether or not pregnancies were intended. Furthermore, interventions were often not clearly defined, had multiple aims and did not indicate which elements were intended to address which aims. Nearly all of the studies were conducted in the USA and focused largely on African American or Hispanic and Latina American populations. CONCLUSIONS We found no evidence to indicate that existing interventions to reduce repeat teenage pregnancy were effective; however, subsequent births were reduced by home-based interventions. Qualitative and realist evidence helped to explain gaps in intervention design that should be addressed. More theory-based, rigorously evaluated programmes need to be developed to reduce repeat teenage pregnancy in the UK. STUDY REGISTRATION This study is registered as PROSPERO CRD42012003168. Cochrane registration number: i=fertility/0068. FUNDING The National Institute for Health Research Health Technology Assessment programme.