The Positive Choices trial: study protocol for a Phase-III RCT trial of a whole-school social marketing intervention to promote sexual health and reduce health inequalities.

non-competent last sex; age at sexual debut; non-use of contraception at first and last sex; number of sexual partners; dating and relationship violence (DRV) victimisation; sexually transmitted infections; pregnancy and unintended pregnancy for girls and initiation of pregnancy for boys using adapted versions of the RIPPLE measures. Ethics review: LSHTM research ethics committee (reference 26411). Completion data: 1/3/25. Sharing statement: Data will be made available after the main trial analyses have been completed on reasonable request from researchers with ethics approval and a clear protocol. Amendments to the protocol will be communicated to the investigators, sponsor, funder, research ethics committee, trial registration and the journal publishing the protocol. Amendments affecting participants' experience of the intervention or important amendments affecting the overall design and conduct of the trial will be communicated to participants.