The main aim of this study was to compare fertility in minor (Sunnah) and major (Shia) religious groups of Iran after matching the two groups by some confounding factors. 12,099 data of population and census survey of Iran in 2011 in two provinces of Guilan and Kurdistan were used in this study. Propensity scoring matching method was used for matching two groups. First confounder variables were found and after that the groups were matched. Principal component analysis was used to make a socioeconomic (SES) variable. At the end, two groups were compared to each other by nearest neighborhood method. Also Poisson regression was used to find the effective factors of fertility. Before using matching method, the results showed that fertility in Kurdistan was higher than Guilan, but after matching, fertility in Guilan was higher. The results of regression model showed that in Guilan, living in urban region, age and level of education had effect on fertility, but in Kurdistan, education, age and SES were effective factors.
Keywords: Fertility; Guilan; Kurdistan; Minority; Principal component analysis; Propensity scoring; Shia; Sunnah.