Summary: The main objectives of this thesis are two: First, investigate patterns of fertility decline of marriage in Spain, and more specifically their differences space (at the provincial level) in the last decades of the nineteenth century and beginning of the twentieth. Secondly, shed some light on the type of method of birth control (recreational or limitation) used by married women at least once in those provinces where the marital fertility was declining. This research has been done using data on the number of live births declared by married women and widows in the Spanish census of
1920, 1930 and 1940. Most of the research on the fertility transition in Spain have been based on information from Resurtió Civil rates to estimate age-specific fertility (nationally) only since 1922, or by using indirect methods for estimating population applied the sex and age structure of the population and to calculate indicators of fertility indicators such as Princeton or Child-Woman Ratios (ratio of children per woman). However, this is the first time back data on fertility from these three censuses are used in a manner so intensively. This fact, together with the well-known biases affecting the information retrospect, have demanded severe conduct a critical assessment of the data, as well as correct when it is needed. This critical evaluation has shown positive results in the three censuses, with the exception of half a dozen provinces in the Census of 1920 that showed data is not credible. The main results obtained from the analysis of these data sources can be summarized in the following points: * The parity declared by women ever married shows a slow but gradual decline in fertility marriage in Spain in the early decades of the twentieth century , which accelerated from the 30's. * Backwards data on the number of live births show some spatial patterns of marital fertility highly differentiated. * The likelihood of an enlarged at the provincial level show that the fertility transition was a shift in the methods of birth control, with a succession of three successive transitions: adjustment phase, phase of innovation and ideas, and innovation phase the methods. These phases or stages involved the move from a situation of lack of control to another control type spacing, and finally a control type stopping. As a final result, it has been established even typology of the Spanish provinces according to the transitional state in which they were between 1920 and 1930, from the data on the levels of marital fertility and the likelihood of an enlarged derived from the Census 1920 and 1930 (can not calculate the odds of enlargement from Census 1940). This typology, with four groups of provinces according to their level of parity and the use of methods of birth control, shows that the fertility transition marriage was a common phenomenon that affected all territories but with differences in timing very important. The Catalan provinces were the pioneers, while the provinces of Castile, and the Canary Islands, along with some Andalusian provinces, began the fertility transition in last place, probably in the fourth decade of the twentieth century.
