A systematic review of studies of fertility decline in the last two decades

In recent decades, Iran has experienced significant fertility decline. The sharp decline in fertility in Iran, has attracted the attention of many experts and much research has been done in this area. This article is a review of research on fertility decline in the two decades leading up to 1390. The purpose is to combine fertility decline research results to achieve a macro analysis and integration of research results. This article reviews the findings of 50 research titles, which have been screened and selected by multiple criteria. In this review, the research is presented in the form of four components (time interval, researcher gender, type of source and specialized domain of authors) and their methodology in the form of three components (research method, statistical population and sample size) and research findings as the most frequent determinant of fertility decline in Iran, it is mentioned. The results show that the theory of population transition is the main theoretical topic during several decades of demographic studies in Iran. In these studies, the explain the sharp decline in Iranian fertility has been studied through structural components. Also, a review of these studies shows that most of them, with a small sample size and a different statistical population, have traversed the same, common path and achieved almost identical results. Therefore, changing the statistical population or Sample and repeating the structural determinants of fertility reduction in several studies does not lead to any knowledge in this field.