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

Identifying the effects of large catastrophic shocks on the distribution of births using a combination of Benford's law and the Vector Error Correction Model(VECM)

This study examines the case of Romanian births, jointly distributed by age groups of mother and father, covering the period 1958-2022, under the potential influence of significant disruptors. Demographic shocks like armed conflicts, epidemics, floods, or slave trade are already present in the literature. Therefore, our study searches for the effects of World War II, the 1966 Anti-abortion Decree and COVID-19 shocks on birth distribution. Other legislative and political changes are not marginalized. Applying First Digit Law of Benford we search for anomalies in birth data. Then, following a vector-autoregressive method, we search for a long-term relation between fertility rate and anomaly in birth distribution. We also try to link disruptors and their potential effects as well. We found a statistically significant long term relation between fertility rate and birth distribution by age of parents. We confirm World War II as a major shock, and our results suggest adding the 1966 Anti-abortion Decree to the list of catastrophic events. The current work also reveals a time lag of 15 years between shock and its effects and a persistence of 15 to 20 years. COVID-19 does not impact (yet) the birth distribution by age of parents.

Anomalous distributions of birthdates across days of the month: An analysis using Spanish statistical records

This study investigates birthdate patterns in a context of well-established civil registers and intensive migration inflows. Leveraging extensive Spanish microdata on residential variation flows and the Spanish Municipality Register, this research reveals new facets of the distributions of immigrants' birthdates across days of the month that differ significantly from those of non-migrants. The registered days of the month for birthdates are categorized into six distinct types based on the assumption that the anomalous distributions of birthdates will display rounding or simplifying patterns (digit preferences). The investigation reveals important anomalies in the distribution of birthdates that are much more pronounced for immigrants. A notable concentration of recorded birthdates is confirmed within all the designated types, contrasted by an under-recording of births on the remaining days of the month. These anomalies depend primarily on migrants' country of origin and age group. The paper ends by proposing some recommendations for mitigating the anomalies.

Studying the seasonality of conceptions among five distinct population subgroups in mainland Greece: a story of similarities and variability

The paper studies seasonality of conceptions among five distinct population subgroups of mainland Greece for the period 1951-2002. The populations explored include those residing in Metsovo, Dion, Organi, Kehros, as well as a "General" Sample consisting of persons located in various areas of continental Greece. The populations under investigation present diverse characteristics regarding religion, cultural background, socio-economic status etc. Records of births were derived from the Vital Registration System of the respective municipalities and communities of the populations under research were constructed. The date of child conception was estimated as the recorded date of birth minus 260 days.The analysis focuses, among others, on the construction of seasonal indices, applying a variant ratio to moving averages method which reveal, in relative terms, the seasonality of the phenomenon. Subsequently, these ratios are considered as the dependent variable in regression models while months, expressed in terms of dummy variables, are introduced as predictors. Four main sub-periods are considered; 1951-64, 1965-80, 1981-92 and 1992-2002. The findings show that the extent of seasonality differs between periods as well as between the five population subgroups though the phenomenon becomes less prominent over time in all cases. There is a tendency of an increased number of conceptions among mountainous populations during summer, irrespective of religion or socio-economic status, possibly partly due to environmental factors (i.e. seasonal workload, domestic organisation of extended families, etc). Nevertheless, the mountainous populations differ regarding the intensity and duration of this phenomenon. By contrast, in Dion, a lowland Christian Orthodox population, conceptions increase after Easter and remain elevated until June.

Reproductive seasonality in the Baka Pygmies, environmental factors and climatic changes

Reproductive seasonality is a phenomenon common to human and animal populations and driven by, among others, climatic variables. Given the currently changing climate and its impacts on both the environment and human lives, the question arises of its potential effects on reproductive seasonality. Few studies have specifically explored the seasonality of reproduction among hunter-gatherers and anyone investigated how current climate change might affect this phenomenon. In this study we addressed reproductive seasonality in the Baka Pygmy living in African rain forests. Since reproductive seasonality can be linked to weather patterns, we explore this possibility. However, climatic variables driving weather patterns have changed over the years, so we assessed whether this has influenced the Baka reproductive pattern. Based on 34 years of written birth records and oral questionnaires from 13 years of systematic fieldwork, we observed a bimodal birth pattern with two birth peaks at 6-month intervals. Our results demonstrate that precipitation at conception or at birth potentially has effects, respectively negative and positive on the monthly number of births; and temperature has a role in controlling other variables that do affect the reproductive pattern. Changing weather patterns appear to be affecting the reproductive seasonality in the Baka, suggesting that attention needs to be given to the influence of global climate change on forager societies.

NDVI predicts birth seasonality in historical Baja California Sur, Mexico: adaptive responses to arid ecosystems and the North American Monsoon

Birth seasonality is a phenomenon whereby populations can be characterized by a single month or season in which births peak. While non-human animal research suggests that seasonal birth-pulses are related to variation in climate and local energy availability, social scientists debate the mechanisms responsible for it in humans. Here we investigate the role of precipitation, temperature, and energy availability on seasonal conception and birth pulses using a historical dataset from the Baja California peninsula - a hot, arid desert that experiences seasonal climatic fluctuations associated with the North American Monsoon. Analyses suggest that 1) local energy availability had a negative relationship with conception pulses; and 2) birth pulses had a positive relationship with local energy availability and a negative relationship with temperature. Taken together, our analyses suggest that women timed conceptions when local energy availability was lowest (challenging expectations of conception rates as simply reflecting ecological influences on female fecundity), so that children were born during the seasonal "green-up" associated with the North American Monsoon. Given our results, we speculate that birth seasonality represents a form of traditional ecological knowledge to improve neonate health and wellbeing.

Lent impact on the seasonality of conceptions during the twentieth century in Spain

In European past populations, religious canons shaped the seasonal distribution of marriages and births by means of banning weddings and sexual intercourse during important holidays within the religious calendar. In contemporary secularized societies, this seasonal modeling has disappeared. A few pieces of evidence have been gathered to explain how they have disappeared. This paper analyzes the impact of Lent on the seasonality of conceptions during the last century in Spain. Data births of the entire Spanish population born in Spain and alive on the first of January 2003 (more than 39 million) containing the date, size of the municipality (six groups) are used. To analyze this seasonality, we have used time-series techniques. We have built an ad hoc temporal regressor starting from the number of days of Lent that corresponds to each month. We have also used regression models with autoregressive and moving average errors (regARIMA models) to estimate, by maximum likelihood, the set of model parameters. The paper gathers new evidences about the importance of religion on the preproduction of Spanish population until very recently. They show that during the twentieth century, in Spain, there were a significant decrease in conceptions during Lent and a significant rebound after this period. We note that this previous effect disappeared in 1975-1980, when both democracy and the contraception revolution began in Spain. After this period, the seasonality of birth in general disappears.

Getting a head start: turn-of-the-month submission effect for accepted papers in management journals

Intriguing unforced regularities in human behaviors have been reported in varied research domains, including scientometrics. In this study we examine the manuscript submission behavior of researchers, with a focus on its monthly pattern. With a large and reliable dataset which records the submission history of articles published on 10 multidisciplinary journals and 10 management journals over a five-year period (2013–2017), we observe a prominent turn-of-the-month submission effect for accepted papers in management journals but not multidisciplinary journals. This effect gets more pronounced in submissions to top-tier journals and when the first day of a month happens to be a Saturday or Sunday. Sense of ceremony is proposed as a likely explanation of this effect, since the first day of a month is a fundamental temporal landmark which has a ‘fresh start effect’ on researchers. To conclude, an original and interesting day-of-the-month effect in the academia is reported in this study, which calls for more research attention.