Widening Regional Economic Disparities and Fertility Decline in South Korea: A Cross‐Level Analysis

ABSTRACT Regional economic disparities and fertility decline have intensified concurrently in South Korea, yet few studies have directly examined their relationship. This study investigates how widening regional inequality, a spatial form of socioeconomic stratification, influences fertility outcomes by applying Yitzhaki's relative deprivation index. Using spatial panel models with two‐way fixed effects for 229 districts from 2015 to 2021 and multilevel models of married women aged 19 to 49 from the 2020 Population and Housing Census, the analyses consistently demonstrate negative associations between regional disparity and fertility. In the spatial panel analysis, growth in disparity reveals a significant negative effect on crude birth rates, while the multilevel models confirm that regions with sharper increases in inequality recorded fewer births per woman. These findings suggest a potential mechanism through which the demographic–economic paradox operates and provide empirical support for extending relative deprivation theory to the regional scale.