Fertility has undergone profound transformations during the last three decades in Spain, as a result of various societal and economic transformations such as women’s greater access to the labor market, transition to university education, and rise of cohabitation, just to cite a few factors. Such transformations did not impact childbearing evenly, but rather heterogeneously highlighting important regional differences, especially in those regions with strong cultural and linguistic identities. In this article we test the relationship between fertility and various socio-economic variables using spatial panel analysis for 910 Spanish territorial units (comarcas) from 1981 to 2011 census and vital register data. We find that fertility presents clear spatial autocorrelation both at global and local scale, and that clusters exhist across the country consistently with regional identities, although such divisions change substantially with time. We investigate the transformation of childbearing patterns using three spatial panel models that control for individual effects, time effects and separate spill-over effects in the independent variables across space and over time. Our results show that a change in demographic regimes between 1981 and 2011, as well as a positive impact of out of wedlock births and the decrease in marriage rates on fertility and on mean age at first birth.