Do Suburbs Have Higher Fertility than Central Cities? Diversity of Regional Differences in Population Reproduction Within Metropolitan Areas in Japan

Observing the distribution of fertility and clarifying its mechanisms are important for discussing sustainability of population reproduction. This study investigated regional fertility differences within Japanese metropolitan areas to test the validity of the hypothesis that fertility is lower in central cities and higher in suburban areas. Additionally, the relationship between urban life cycles and fertility trends was explored. Data from the “Specified Report of Vital Statistics” between 2000 and 2015 was used. The findings reveal that, though large metropolitan areas such as Tokyo, Osaka, and Nagoya exhibit significantly lower fertility in specific central wards, this pattern is not applicable to all Japanese metropolitan areas. Numerous small to medium-sized metropolitan areas exhibit diverse fertility distribution patterns, with some central cities recording higher fertility rates than their suburbs. The results suggest that regional fertility differences in Japan are shaped by a complex interplay of urban development, housing policies, and demographic behaviors rather than a simple dichotomy between central cities and suburbs. This study highlights the need for further interdisciplinary research integrating population geography and urban studies to refine the understanding of fertility variations within Japanese metropolitan areas.