Background <p>Effective non-pharmacological options for labour analgesia remain limited. Lamaze breathing may provide modest analgesic benefits. The crossed-hands effect, associated with altered somatosensory processing, may modulate pain through sensorimotor mechanisms. This trial evaluated whether adding an arms-crossing technique to Lamaze breathing reduces labour pain during the latent phase of labour.</p> Methods <p>This single-centre, single-blinded, parallel-group randomised controlled trial was conducted in the obstetric unit of a hospital in China between April and June 2024. Sixty women in the latent phase of labour were randomly assigned (1:1) to either Lamaze breathing plus an arms-crossing technique (intervention group, <i>n</i> = 30) or Lamaze breathing alone (control group, <i>n</i> = 30). The arms-crossing technique involved repeatedly crossing both arms across the body midline synchronised with rhythmic breathing during uterine contractions. Outcome assessors were blinded to group allocation. The primary outcome was labour pain intensity measured using a numerical rating scale across five consecutive contraction cycles. Secondary outcomes included heart rate and pulse oxygen saturation (SpO₂) during contractions and contraction intervals. Analyses were conducted on an intention-to-treat basis.</p> Results <p>All 60 participants completed the study and were included in the analysis. Baseline characteristics were comparable between groups. Pain scores decreased over time in both groups; however, the intervention group showed significantly greater reductions in pain scores than the control group. Repeated-measures analysis demonstrated a significant time-by-group interaction for pain scores (F = 6.109, <i>P</i> &lt; 0.001, partial η² = 0.095), with significant between-group differences observed at the fifth contraction cycle (F = 4.742, <i>P</i> = 0.034, partial η² = 0.076). No significant group differences were observed for heart rate or SpO₂ during contractions. SpO₂ during contraction intervals differed significantly between groups (F = 6.824, <i>P</i> = 0.011, partial η² = 0.105), although values remained within normal physiological ranges. No adverse events occurred.</p> Conclusions <p>Adding an arms-crossing technique to Lamaze breathing significantly reduced labour pain without observable adverse effects. The arms-crossing technique may represent a simple and feasible non-pharmacological strategy for labour pain management.</p> Trial registration <p>Chinese Clinical Trial Registry, ChiCTR2400083201. Registered 18 April 2024.</p>