Effect of religious rules on time of conception in Romania from 1905 to 2001

Abstract: Population growth (or decay) in a country can be due to various f socio-economic constraints, as demonstrated in this paper. For example, sexual intercourse is banned in various religions, during Nativity and Lent fasting periods. Data consisting of registered daily birth records for very long (35,429 points) time series and many (24,947,061) babies in Romania between 1905 and 2001 (97 years) is analyzed. The data was obtained from the 1992 and 2002 censuses, thus on persons alive at that time. We grouped the population into two categories (Eastern Orthodox and Non-Orthodox) in order to distinguish religious constraints and performed extensive data analysis in a comparative manner for both groups. From such a long time series data analysis, it seems that the Lent fast has a more drastic effect than the Nativity fast over baby conception within the Eastern Orthodox population, thereby differently increasing the population ratio. Thereafter, we developed and tested econometric models where the dependent variable is the baby conception deduced day, while the independent variables are: (i) religious affiliation; (ii) Nativity and Lent fast time intervals; (iii) rurality; (iv) day length; (v) weekend, and (vi) a trend background. Our findings are concordant with other papers, proving differences between religious groups on conception, - although reaching different conclusions regarding the influence of weather on fertility. The approach seems a useful hint for developing econometric-like models in other sociophysics prone cases.