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Abstract: Seasonality of births is in some populations strongly
influenced by sociodemographic factors. In this study, we analyse the impact of
mothers’ sociodemographic characteristics for the seasonal variation in
7,710,955 live births in Sweden between 1940 and 2012. During 1940-1999,
Swedish birth rates showed the typical seasonal variation with high numbers of
births during the spring, and low numbers of births during the last quarter of
the year. However, during the twenty-first century, the seasonal variation in
fertility declined so that only minor variation in birth rates between February
and September remains. Still, the pattern of low birth rates at the end of the
year remains and has even become more pronounced in recent decades. The roles
of maternal education, mother’s birth country, parity, and instances where the
mother has re-partnered between subsequent births changed during the second
half of the twentieth century. The study underlines that in a society with low
fertility and efficient birth control, active choices and behaviours associated
with an individual’s sociodemographic characteristics tend to matter more for
the seasonal timing of childbearing than environmental factors related to the
physiological ability to reproduce and cultural-behavioural factors related to
the frequency of intercourse.
Swedish Research Council (Vetenskapsrådet) via the Swedish Initiative for Research on Microdata in the Social and Medical Sciences (SIMSAM): Stockholm University SIMSAM Node for Demographic Research, Grant Registration Number 340-2013-5164.