A news story earlier this week reported an increased number of births during the summer months in Norway. According to the story the peak in births used to be in the spring months, nine months after summer vacation, but is now during the summer. The midwifes thinks this change is because of the rules for granting a place in preschool day care. Children born before september 1st are legally entitlet to a place in day care.
Anyway i decided to try to visualize this. I found some data at the Statistics Norway website, loaded it into R, cleaned it, restructured it etc. and made this animation with ggplot2 showing the monthly distribution of births from year 2000 to 2011. I decided to include data for the years before 2005 since that is when the current left wing coalition took office and they had a program for universal access to day care. It is hard to spot a definite trend, but the graph for 2011 shows a clear top in the summer months. It will be interesting to see if this becomes clearer the next couple of years. Also, if this becomes a continuing trend, it would be interesting to look at surveys in family planning and see if there has been more of it the last couple of years.
The birthIndex on the y-axis is not the precise number of births for a given month, but is corrected for the number of days in the month. This makes the different months comparable.