Most Scandinavians Are Born During Summer Time and Less Norwegians Are Born the First Quarter of the Year: A Study Comparing Scandinavian Birth Patterns 2000-2012

OBJECTIVES Summer time is a challenging period in obstetric care as many health care workers are on holiday. We aimed to explore the Scandinavian birth patterns and the Norwegian kindergarten reform's possible influence on time of delivery in Norway. METHODS A retrospective analysis using data (2000-12) from the medical birth registries of Denmark, Norway and Sweden was carried out. Annual data for each country were compared. The first five years (2000-2004) period was compared with the periods 2005-2009 and 2010-2012 to clarify any changing trend in month and seasons of delivery. Furthermore, the time period following the Norwegian kindergarten reform (2010-12) was compared with the time period 2000-2009. In total, there were 760,168 Norwegians, 827,354 Danes and 1,354,177 Swedes born during study period. RESULTS Whereas the number of deliveries increased in Sweden (24%) and Norway (3%), there was a 12% reduction in Denmark during study period. Comparing seasons, most births (35.3%) occurred during summer time (May-August). In Norway, there was a significant change during study period with fewer children born between January and April (P < 0.04) and more during summer time (P < 0.01). The lower percentage of births during the last quarter of the year was stable in all countries. CONCLUSION Most Scandinavians were born during summer time. During study period a significant shift of births from spring to summer time was observed in Norwegians. So far, the Norwegian kindergarten reform has not influenced on the birth rate between September and December.