Tehran University of Medical Sciences Iranian Journal of Psychiatry 1735-4587 18 2 2023 03 15 153 164 Hosna Mirzaasgari Department of Clinical Psychology, Faculty of Behavioral Sciences, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. Fereshte Momeni Department of Clinical Psychology, Faculty of Behavioral Sciences, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. Abbas Pourshahbaz Department of Clinical Psychology, Faculty of Behavioral Sciences, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran. Farahnaz Keshavarzi Department of Obstetrics and Gynecology, School of Medicine, Motazedi Infertility Research and treatment Center, Kermanshah University of Medical Sciences, Kermanshah, Iran. Masoud Hatami Department of Oral and Maxillofacial Medicine, School of Dentistry, Kermanshah University of Medical Sciences, Kermanshah, Iran. 2021 08 01 2022 08 03 Objective: The aim of this study was to determine the role played by psychological distress in the relation between personality dimensions and pregnancy outcome of women undergoing in vitro fertilization/Intra-Cytoplasmic Injections (IVF/ICSI) treatment. Method: This prospective cohort study was conducted for 12 months on 154 infertile women who were receiving IVF/ICSI assisted reproductive treatment for the first time. Research instruments for measuring psychological distress included the Fertility Problem Inventory (FPI) and the Depression, Anxiety, and Stress Scale (DASS-21). One of these was completed prior to ovarian stimulation and the other during the embryo transfer stage. The temperament and Character Inventory-Revised (TCI-R 125) was employed once to assess personality dimensions prior to the ovarian stimulation stage. Independent t-test, Mann Whitney test, Repeated Measures and path analysis were performed for statistical analysis of data. Results: The results of this study showed no significant difference between the pregnant and non-pregnant groups in personality traits (Harm avoidance and self-directness) and psychological distress (FPI and DASS scores). Repeated measures showed a significant difference in stress, anxiety, and depression levels between the two stages of ovarian stimulation and embryo transfer (P < 0.01). Path analysis showed no significant direct and indirect effect for harm avoidance on the pregnancy outcome when psychological distress was mediated. Conclusion: The effect of psychological factors on IVF outcomes is more complicated than is generally assumed and more studies are mandatory to clarify the relationship between personality traits and infertility treatments. https://ijps.tums.ac.ir/index.php/ijps/article/view/2846 https://ijps.tums.ac.ir/index.php/ijps/article/download/2846/1105