Background & aim: Dysmenorrhea also known as menstrual cramp or painful period is one of the most prevalent health issues among women. There are contradictory evidence regarding the impact of childbirth on the occurrence of dysmenorrhea. Also, only pain severity has been examined, as one of the clinical features of dysmenorrea in most related literature and the other characteristics of pain including duration, quality, location, as well as the associated symptoms have been overlooked. Therefore, the present study aimed to compare the patterns of primary dysmenorrhea before and after childbirth in primiparous women. Methods: In this cross-sectional study, 124 primiparous women with only one delivery were examined. The multistage sampling method was used to select the subjects who referred to the healthcare centers of Mashhad, Iran in 2010. The research tools included a demographic questionnaire, a form to record menstrual pattern, and verbal multidimensional scoring system for assessment of severity of dysmenorrhea. Data were analyzed by Wilcoxon signed-rank test and Cohen’ s kappa coefficient using SPSS. Results: The findings showed statistical significant differences in all pain characteristics before and three cycles after childbirth including pain severity (P1<0. 001, P2<0. 001, and P3<0. 001), duration (P1<0. 001, P2<0. 001, and P3<0. 001), quality (P1<0. 001, P2<0. 001, and P3<0. 001), location (P1<0. 001, P2<0. 001, and P3<0. 001), and associated symptoms (P1<0. 001, P2<0. 001, and P3<0. 001). Conclusion: According to the results of this study, childbirth could alter the pattern of primary dysmenorrhea including severity, duration, quality, and location, as well as associated symptoms. It seems that childbirth could be accepted as a factor influencing the pattern of primary dysmenorrhea.