1. Introduction
Infertility is among the major problems of marital life. It is associated with many psychological consequences, such as failing to establish high-quality couple relationships and decreased commitment to marriage. In a study, the role of sexual function and relationship quality in predicting marital commitment were investigated. The results indicated that both variables were predictors of marital commitment; the quality of relationship was a stronger predictor of marital commitment compared to sexual function [23]. 
Another study indicated that couples’ relationship quality could predict marital satisfaction and commitment [24]. Infertility can lead to the feelings of helplessness, conflict, frustration, severe loss of self-esteem and reduced self-confidence, withdrawal and isolation, identity crisis, feelings of inadequacy, and the meaninglessness of life [7]. This study aimed to investigate marital commitment and relationship quality among fertile and infertile couples.
2. Methods 
This was a cohort study. The study population consisted of all fertile and infertile couples referring to Sarem Hospital in Tehran City, Iran, in 2016. Of these, 200 samples (96 infertile and 104 fertile) were randomly recruited using Morgan Table. Data collection tools were Adams and Jones marital commitment questionnaire and Khoshkam’s marital relationship quality scale.

3. Results
There was a significant positive relationship between marital commitment and relationship quality in fertile (r=0.27, P<0.05) and infertile (r=0.18, P<0.05) couples. In both groups, there was a significant positive relationship between marital commitment and its dimensions and a significant positive relationship with all relationship quality dimensions. Moreover, the relationship quality was positively and significantly correlated with all of its dimensions, and with marital commitment dimensions of moral and structural commitments; however, it was not correlated with personal commitment dimensions.
The Multivariate Analysis of Variance (MANOVA) results revealed a difference between the two groups in terms of relationship quality and its subscales (problem-solving, communication styles, spouse attention), as well as marital commitment and its subscales (personal, moral, structural). 
An essential limitation of this study was the lack of matching and controlling variables, such as age, infertility duration, age of marriage, and psychological status. This was due to limitations in infertile samples. It is suggested that future studies be conducted with peer groups regarding infertility duration, age of marriage, and psychological health. Additionally, repeating the research using similar population but from different cultural backgrounds can help to improve the theoretical richness and the generalization of the present study results. Furthermore, it is recommended that a relationship enrichment program be organized for infertile couples with the participation of family specialists and counselors.
4. Conclusion
The problem of infertility in marital life has adverse effects on other psychological dimensions of couples, including marital commitment and relationship quality; thus, it challenges their lives. Such unpleasant consequences can be avoided by psychological interventions in this group.
Ethical Considerations
Compliance with ethical guidelines
This study was extracted from an approved proposal (No.2300950517) provided for Sarem Hospital.
Funding
This research did not receive any specific grant from funding agencies in the public, commercial, or not-for-profit sectors.
Authors' contributions
Conceptualization, methodology, software, investigation, resources, writing, review and editing by Saeed Shahhossiani Tajik (contribution rate= 60%); collaborate on the project and problem statement by Najme Taheri (contribution rate= 20%); collaborate on the project, data collection and resources by Masoome Sayadi (contribution rate= 20%).
Conflicts of interest
The authors declared no conflict of interest.
Acknowledgements
The authors would like to thank Dr. Masoud. Gholamali Lavasani (Associate Professor, Faculty of Psychology, University of Tehran) and Dr. Gholamreza Hajati (Assistant Professor, Sarem Hospital) for their valuable cooperation.