Is there an association between family members’ season of birth that could influence birth seasonality? Evidence from Spain and France

Abstract

The number of births varies by season. Research on birth seasonality has shown that women’s season of birth somehow influences that of their children, but factors underlying the intergenerational transmission of birth seasonality remain unknown. With data from Spain and France, we analysed the possibility of transmission of birth season between generations, testing whether relatives tended to be born in the same season. Results indicated that there was an association—a similarity—between parents’ and children’s birth seasons, partially explaining the stability of seasonal patterns over time. This association also existed between parents’ birth seasons. While parents’ association is directly explained by an excess of marriages with spouses born in the same month, the overall association may be explained by two facts: different socio-demographic groups show differentiated birth patterns, and relatives share socio-demographic features. Birth season seems to be related to family characteristics, which should be controlled for when assessing birth-month effects on subsequent social/health outcomes.

Keywords:

• birth seasonality
• season of birth
• association
• similarity
• family
• microdata
• vital statistics

Disclosure statement

No potential conflict of interest was reported by the authors.

Notes

1 Adela Recio Alcaide is a PhD student in the Public Health Unit, Faculty of Medicine and Health Science, University of Alcalá (Spain), and is based in the Institute for Fiscal Studies (IEF), Ministry of Finance, Madrid (Spain). César Pérez López is based at IEF and also at the Department of Statistics and Data Science, Complutense University of Madrid (Spain). Miguel Ángel Ortega is based in the Department of Medicine and Medical Specialties, Division of Research in Embryology and Human Development, Faculty of Medicine and Health Science, University of Alcalá (Spain). Luisa N. Borrell is with the Department of Epidemiology & Biostatistics, City University of New York, Graduate School of Public Health & Health Policy, New York, NY, USA. Francisco Bolúmar is based at both the Public Health Unit, Department of Surgery and Medical Sciences, Faculty of Medicine and Health Science, University of Alcalá (Spain), and the Department of Epidemiology and Biostatistics, Graduate School of Public Health and Health Policy, City University of New York (US).

2 Please direct all correspondence to Adela Recio Alcaide, Public Health Unit, Department of Surgery and Medical Sciences, Faculty of Medicine and Health Science, University of Alcalá, C/ 19, Av. de Madrid, Km 33,600, 28871, Alcalá de Henares, Madrid, Spain; or by E-mail: [email protected].

3 Acknowledgments: Stella Villarmea is gratefully acknowledged for her insightful advice.

4 Funding: This research received no specific grant from any funding agency in the public, commercial, or not-for-profit sectors.

5 Data availability: The Spanish data set underlying this paper was derived from a source in the public domain: Birth Statistics Microdata (from Instituto Nacional de Estadística). The French data set underlying this paper was derived from a custom data request to INSEE: État civil - Naissances: Tabulation sur mesure (from ADISP in 2022).

6 Ethics approval: Retrospective, secondary, anonymized data sets from the national statistics offices of Spain and France were used for the purpose of the present study. The Ethics Committee on Research and Animal Experimentation at the University of Alcalá exempted this research from ethical review because it involved non-identifiable data and data sets are in the public domain or available on request.