Tehran University of Medical Sciences Iranian Journal of Public Health 2251-6085 54 3 2025 03 04 645 653 Sadaf Alipour 1. Breast Diseases Research Center (BDRC), Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran 2. Department of Surgery, Arash Women’s Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Maryam Tabatabaeian Anahid Clinic, Isfahan, Iran Parisa Aziminezhadan Aziminezhadan Breast Clinic, Tehran, Iran Azin Saberi Department of Surgery, Arash Women’s Hospital, School of Medicine, Tehran University of Medical Sciences, Tehran, Iran Maryam Daneshpazhooh 1. Autoimmune Bullous Diseases Research Center, Tehran University of Medical Sciences, Tehran, Iran 2. Department of Dermatology, Razi Hospital, Tehran University of Medical Sciences, Tehran, Iran Ramesh Omranipour 1. Breast Diseases Research Center (BDRC), Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran 2. Department of Surgical Oncology, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran Paniz Famil-Amir Aziminezhadan Breast Clinic, Tehran, Iran Najmeh Ahmadi Anahid Clinic, Isfahan, Iran Maryam Sarkardeh 1. Department of Surgical Oncology, Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran 2. Department of Surgery, Imam Reza Hospital, Mashhad University of Medical Sciences, Mashhad, Iran Nahid Nafissi Clinical Research Development Center (RCRDC), Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran Azita Mazinani Clinical Research Development Center (RCRDC), Rasoul Akram Hospital, Iran University of Medical Sciences, Tehran, Iran Azadeh Joulaee Department of Surgery, Shahid Beheshti University of Medical Sciences, Tehran, Iran Shahla Astaraki Anahid Clinic, Isfahan, Iran Zohreh Zahernia-Shahrbabaki Anahid Clinic, Isfahan, Iran Reihane Tahery-Mehr Breast Diseases Research Center (BDRC), Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran Maryam Gharini-Ahmadi Department of Nursing, Arash Women’s Hospital, Tehran University of Medical Sciences, Tehran, Iran Behnaz Khajeh-Ali-Beiki Department of Nursing, Arash Women’s Hospital, Tehran University of Medical Sciences, Tehran, Iran Marzieh Orouji Department of Nursing, Arash Women’s Hospital, Tehran University of Medical Sciences, Tehran, Iran Bita Eslami Breast Diseases Research Center (BDRC), Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran 2024 02 10 2024 10 11 Background: Idiopathic granulomatous mastitis (IGM) is a chronic breast disease with unknown pathophysiological and clinical aspects. Therefore, we designed this multi-center prospective case-control study to explore and clarify the risk factors with an acceptable sample size. Methods: From March 2021 to December 2023, five hundred-four women with a histologically proven IGM were entered into the IGM group and 504 women with healthy breasts were included in the control group across nine centers. Participants' information was obtained by trained staff. Multivariate binary logistic regression was used to estimate the odds ratio (OR) and 95% confidence intervals (CI) for the associations between variables and IGM. Results: The mean age of all participants was 34.92 ± 7.12 yr. The previous history of diseases as a whole, was significantly higher in the IGM group (33.1%) compared with the control group (26.6%). Logistic regression showed that previous lactation (OR= 7.51, 95% CI= 2.37-23.77) and a positive history of diabetes (OR = 4.23, 95% CI= 1.32-13.51) had a positive association with IGM, while OCP use (OR = 0.70, 95% CI= 0.52-0.93) was associated with IGM reversely. Conclusion: The history of breastfeeding and not its duration is associated with a 7-fold increase in the rate of IGM. Furthermore, previous history of diabetes is a risk factor, while OCP use is a protective factor against IGM. We are designing another study to further investigate the relationship between breastfeeding, milk stasis, and IGM, based on our findings. https://ijph.tums.ac.ir/index.php/ijph/article/view/34596 https://ijph.tums.ac.ir/index.php/ijph/article/download/34596/8503