The Decline of Spanish Fertility: The Role of Religion.

The Spanish total fertility rate declined from 2.8 to below 1.4 children per woman from 1975 to 2020. Spain is categorized as a "lowest-low fertility" country. Although there have been many attempts to explain the Spanish fertility decline, there has been an insufficient focus been given to religion. This brief report aims to analyse how religious affiliation, particularly being Catholics, associates with fertility behaviours-entering parenthood and the total number of children. Using three nationally representative surveys, we show that, compared with the religiously non-affiliated, Catholic women have a higher likelihood of entering parenthood after controlling for demographic, union status and educational characteristics. After controlling for changes in education and union formation, changes in religious affiliation account for approximately 4% of the cohort variation in the age at first birth, but there is no significant contribution for men nor to the total number of children for both sexes. Supplementary Information: The online version contains supplementary material available at 10.1007/s10680-022-09644-1.