Midsummer in Sweden equals sun, herring, snaps, flowers and dance around the Maypole. And baby breeding. At least it has been—for a long time, spring was the time when most babies were born in Sweden. Somewhat jokingly perhaps, many explained that high number of births on the Midsummer celebrations. The most common birth date in Sweden is March 22; count backward nine months and you end up on, yes, you guessed it, Midsummer. “There are theories that it is the endless light and the number of sun hours, that are factors to why there are variations in the number of births,” says Lena Lundkvist, demographer at Statistiska Centralbyrån (Statistics Sweden).

“That many are born in the spring may also be the result of vacations.” However, more recent statistics indicate that Swedes have broken the pattern. Last year, July 10 was the day when most babies were born. And looking at births by month, it was May, July and August which had the highest numbers of newborns. “One explanation may be that more people plan when they are going to have their babies. It can be good to give birth in the middle of the summer, when both parents can take off from work.” The least number of babies were born in December. “With the help of contraception you can plan the timing of your baby’s birth fairly well, or at least when you do not want to have children. Many people may not want to have a child who shares his or her birthday with Christmas,” says Lundkvist.