Efficacy of photobiomodulation in perineal trauma after vaginal delivery: a protocol for a randomized, blinded clinical trial.

OBJECTIVE: To evaluate the efficacy of photobiomodulation (PBM) in reducing perineal pain and obstetric vulvar edema, as well os its effects on maternal functioning during the immediate postpartum period. METHODS: This randomized, controlled, double-blind clinical trial protocol will include women aged over 15 years, within 12 h after vaginal delivery, presenting with first- or second-degree perineal trauma and/or vulvar edema and pain ≥ 3 on the Numeric Rating Scale. Participants will be randomized in blocks of four to receive PBM or a sham intervention alongside usual postpartum care. A single PBM session will be performed using 808-nm infrared laser light at an output power of 100 mW. Assessments will be performed at baseline, immediately after the intervention, 12 h, 40 days, and three months postpartum. Outcomes will include pain, pressure pain threshold, vulvar edema area, maternal functioning, treatment satisfaction, urinary incontinence, and sexual function. Statistical analysis will follow the intention-to-treat principle using linear mixed-effects models, with group, time, and group × time interaction as fixed effects and participant as a random effect. Post-hoc comparisons will use Bonferroni correction, with a significance level of 5%. CONCLUSION: PBM is expected to reduce perineal pain and vulvar edema and improve maternal functioning. The randomized design, sham control, blinded outcome assessment, and longitudinal analysis are expected to provide evidence regarding the efficacy and safety of PBM as a non-pharmacological strategy for postpartum care. TRIAL REGISTRATION: Brazilian Clinical Trials Registry (REBEC), RBR9sgdsm2, approved on July 7, 2026.