One day is not as good as another...at least not across the entire territory of Italy:an analysis of the differences in the dailydistribution of births across Italianmacro-regions, 1999–2016

The concentration of births on working days compared to a relative lack of events at weekends or during public holidays has been interpreted in literature as evidence of an excessive appeal to elective delivery. The World Health Organization has repeatedly expressed concerns about the abuse of this practice. We investigate the daily distribution of births in Italy in the period 1999–2016 to answer the following question: In addition to the weekend effects found in other countries, do popular beliefs about “unlucky” days also influence the calendar of births? We assume that without the effects exerted by the working calendar and/or by popular beliefs, the births should be equally distributed between the days of a month. We interpret the equal distribution as the expected one. This allows us to calculate a daily excess of births with respect to the expected number. We evaluate, by the means of multivariate regression, the impact of public holidays and of popular beliefs on the daily excess of births. In addition to working calendar effects, we found a depressing effect exerted by the 17th day of each month in all Italian territories. Indeed, the number 17 is considered extremely unlucky by popular tradition in Italy. We believe that these findings are indicative of a systemic abuse of elective delivery, especially in Southern Italy. To the best of our knowledge, this work is the first to analyze the effect of irrational beliefs on the calendar of births.