BACKGROUND: Labor pain varies significantly among pregnant women, ranging from mild to extremely distressing. Nonpharmacologic pain relief methods during vaginal birth are increasingly popular, either as a complement to pharmacologic agents or, at times, as the primary method of pain relief. Multiple trials have reported that manual or by-hand massage reduces labor pain. The effectiveness of full-body mechanical massage using electric massage chairs on labor pain remains unexplored. OBJECTIVE: This study aimed to evaluate mechanical massage using an electric massage chair on labor pain in nulliparous women. STUDY DESIGN: A randomized counterbalanced crossover trial was conducted in a university hospital in Malaysia from August 2022 to February 2023. Eligible nulliparas in labor with a minimum labor pain score of 5 (0-10 numerical rating scale) were enrolled. Participants were randomized to 30 minutes on the massage chair with mechanical massage followed by 30 minutes on the massage chair without mechanical massage or the other way around in the massage sequence. The primary outcome was a change in pain score comparing pain with and without mechanical massage as a paired comparison for the entire trial participants. The secondary outcomes were across arms analyses of maternal and neonatal outcomes. The paired t test, t test, Mann-Whitney U test, chi-square test, and Fisher exact test were used as appropriate for the data. RESULTS: Overall, 208 women were randomized: 104 to each intervention. Data were available from 204 participants (103 randomized to massage first and 101 to no massage first). The primary outcomes of change in labor pain scores (0-10 numerical rating scale) after massage and no massage (all participants included after crossover, paired t test analysis) were 4.51±2.30 and 5.38±2.10, respectively (mean difference, -0.87; 95% confidence interval, -1.14 to -0.59; P<.001), a significant reduction in pain score after electric chair mechanical massage compared with no massage. On the across randomized arms secondary analyses, labor pain scores after their first massage chair session were 4.35±2.52 (randomized to massage first, received massage as initial intervention) and 5.66±1.73 (randomized to no massage first, received no massage as initial intervention) (mean difference, -1.31; 95% confidence interval, -1.91 to -0.748; P<.001), a significant reduction after mechanical massage. Other distal maternal outcomes (mode of delivery, labor analgesia, duration of labor, and maternal agreement that mechanical massage is effective for labor pain) and neonatal outcomes (Apgar scores at 1 and 5 minutes, cord artery blood pH and base excess, and neonatal admission) were not different across randomized arms. CONCLUSION: Mechanical massage using an electric massage chair significantly reduced labor pain, offering a potential nonpharmacologic pain management option during labor.