Mohamadi 2021.

Study characteristics
Methods	Study design: cluster‐RCT Duration of study: the study was conducted during the academic year of 2018‐2019. Country: Iran Income classification: upper‐middle income country in 2018‐2019 Geographical scope: urban and suburban area of Shahroud Healthcare setting: schools
Participants	1. Age: mean age of students was 14.44 ± 0.51 years. 2. Gender: female 3. Socioeconomic background: not specified 4. Educational background: students Inclusion criteria: eighth grade students with Iranian nationality. Exclusion criteria: a. consumption of psychiatric drugs; b. having family problems such as death or divorce of parents in the past 6 months; c. not attending two consecutive classes and not cooperating with the researcher during the study. Note: at baseline, the intervention (1 and 2) and control group scores for Standard Symptom Checklist‑25, Persian version (SCL‑25) were, respectively, 52.56 (3.05); 50.74 (2.80); and 51.49 (3.61). Stated purpose: to compare the motivational interview and peer groups in promoting mental health and knowledge and performance about puberty health in adolescent girls
Interventions	Name: group counselling Title/name of PW and number Intervention 1: master in consultation in midwifery Intervention 2: peer students 1. Selection Intervention 1: not specified Intervention 2: active volunteers who scored higher on the puberty health questionnaire prior to the start of the study 2. Educational background Intervention 1: master in consultation in midwifery Intervention 2: students 3. Training Intervention 2: in one session, the educational content was explained to peer educators by the researcher. 4. Supervision Intervention 2: peer‐to‐peer educators’ relationship with the researcher continued after the intervention so that educators could ask their questions. 5. Incentives/remuneration: none Prevention type: universal – all adolescent girl students were eligible for inclusion and their baseline scores for the SCL‑25 were well below the cut‐off for the measure. Intervention details Intervention 1—group counselling: motivational interviewing was presented to students (groups of 7‐9 students) by a master in consultation in midwifery during five sessions of 60 to 90 minutes and one session per week. Intervention 2—peers: one formal training session was held by peer educators to other students, and the information was then passed on informally to peers in small groups (5 to 6 students) within 1 month. Each peer educator was responsible for transmitting information to 5 to 6 other students. Control: waiting list – no intervention (after sampling and intervention, two training sessions on puberty health were conducted by the researcher).
Outcomes	Participants’outcomes of interest for this review Distress/PTSD symptoms – SCL‑25 Note: we included data from the peers and control group. Carers’ outcomes of interest for this review Nil Economic outcomes Nil Time points: baseline, post‐intervention (< 1 month, 1‐6 months)
Notes	Source of funding: none Notes on validation of instruments (screening and outcomes): Persian version of SCL‑25 questionnaire. Cronbach’s alpha for the short‐form questionnaire of mental health is 0.97. Additional information: none Handling the data: not applicable Prospective trial registration number: IRCT20180209038675N1