Introduction : Considering the painfulness of labor, the present study was performed aimed to investigate the effect of Citrus Aurantium aroma on the level of pain in the active phase of first labor.

  Methods: The present research has been done as a clinical trial study on 126 nulliparous women (63 subjects in intervention group and 63 subjects in control group) admitted to Valie-Asr hospital in Toyserkan. In aromatherapy group 4ml essence of Citrus Aurantium impregnated gauze, and in the control group, only 4ml normal saline impregnated gauze were attached to their dress collar, and the administration was repeated every 30 minutes. The pain severity was measured at the beginning of the study in both groups and in dilatations 3-4, 5-7, and 8-10cm phase after intervention .Participants were followed up until the delivery time. The data were collected through demographic and obstetric questionnaire, observation checklist, and pain numerical rating scale. The data were then analyzed through using independent t-test, Man Withny-u and chi square.

  Results: The mean pain severity score after the intervention in intervention group in dilatation 3-4 cm (4.97± 0.74), 5-7 cm(6.65± 0.48) and 8-10cm (7.57± 0.56) decreased significantly (P=0.001) compared with control group in dilatation 3-4 cm (8.08± 0.67), 5-7 cm(8.67 ±0.56) and 8-10 cm(9.46± 0.53)

  Conclusion: The findings of the study revealed that aromatherapy of Citrus aurantium essence alleviates the labor pain therefore, this method is recommended to reduce the labor pain.

  Key words: Aromatherapy, Citrus Aurantium, Complementary Medicine , Labor Pain, Medicinal Plants .