Foto: Deyan Georgiev/Mostphotos
A Valentine's baby - not a common sight in Sweden. Photo: Deyan Georgiev/Mostphotos

Between 1940 and 1999 in Sweden, births used to peak nine months after Midsummer and Christmas respectively. As abortion became more accessible, and contraception came more fully into play -- especially for the unmarried -- the seasonal patterns began to reflect more planning of when parents prefer to have their children. This result is clearly shown in a new study by demographers Johan Dahlberg and Gunnar Andersson. They used register data on live births between 1940 and 2012 in Sweden to study this phenomenon.

– Less and less children are born at the end of the year. This means that November - nine months after Valentine’s day - is actually during the period of time when the least number of babies are born. The plausible reason is that parents are planning against having their babies at the end of the year – a pattern that can be seen in other countries as well.  says Gunnar Andersson, professor of Demography at Stockholm University and co-author of the study.

In fact, the only seasonal variation left for births in Sweden are these low birth rates at the end of the year. This pattern has also gained in magnitude.

– Since Valentine’s day is also a new phenomenon in Sweden – and limited to one day – it has absolutely no positive effect on birth rates in this country, says Gunnar Andersson.

Previous studies have shown that children who are born late in the year have disadvantages in school compared with classmates born earlier during the same year, as they become junior in their year group.

– We believe that the  strong cut-off in births at the end of the year is because parents want to avoid giving their children a disadvantage in school, says Johan Dahlberg, researcher in Demography and first author of the study.

More about the research

J Dahlberg, G Andersson; Changing seasonal variation in births by sociodemographic factors: a population-based register study, Human Reproduction Open, Volume 2018, Issue 4, 1 September 2018, hoy015, https://doi.org/10.1093/hropen/hoy015

Contact 

Gunnar Andersson, professor of Demography, telephone +46(0)8 16 32 61, gunnar.andersson@sociology.su.se or Johan Dahlberg, researcher in Demography, telephone +46(0)73 708 26 84, johan.dahlberg@sociology.su.se