The purpose of this paper is to investigate the differences in value of children between the 1960s, 1970s, after 1980 birth cohort, and identifying the factors affecting. The data for this study are drawn from a survey in Semnan province in 2012. Information is related to 405 married women aged 15-49 years. The result shows that the highest score of the children value belonged to the 1960 birth cohort. Protect, emotional and family continuity value in childbearing are characteristics of this cohort. In contrast, emphasis on the economic costs and lost opportunity costs, emotional and psychological benefits to children are characteristics of the 1980 birth cohorts. Based on this study, in line with the socio- economical changes, significant changes in childbearing attitude have emerged in three cohorts. Nevertheless, the 1960 birth cohort more than any other generation produces modern childbearing values and behaviors gives great importance to childbearing and because of the emotional value of children, one of the goals of younger cohort is childbearing. Multiple classification analysis showed that by controlling the effect of factors related to modernization and individual characteristics of respondents, the mean score of value of children within cohort changes. A more percent of the differences between the cohorts are affected by education variable. After entering these variables are considerably reduced the intensity of relationship between value of children and birth cohort. But, the differences in the value of children in three cohorts are still significant.