Christmas cracker: NZ’s most common birthday
It’s true. The statistics bear it out. New Zealand babies are far more likely to be conceived at or around Christmas than any other time of the year.
According to numbers compiled by StatsNZ covering births from 1980 to 2017, the most common birthday in New Zealand is September 29.
An average full-term pregnancy is 40 weeks; this date is 40 weeks and one day after Christmas.
In further evidence that the Christmas season really gets us in the festive spirit, the top 10 most common birthdays in New Zealand all fall between September 24 and October 4.
While the exact date differs, September is the most common month for births in countries including the United States, Britain and Australia.
After February 29 – unsurprisingly the least common birth date, given it only happens once every four years – the least likely day to be born in New Zealand is December 25, Christmas
Day, followed by Boxing Day. January 1 is number 363 of 366, while January 2 is 362.
But the explanation for this goes deeper than when Kiwis are most likely to be getting busy.
Close to 20 per cent of women giving birth in New Zealand have an elective caesarean, which usually means they choose the date their baby will be born in advance. Most people won’t choose a public holiday, either because they don’t want their child to have their birthday on an already significant date or because they are dissuaded from doing so (some hospitals don’t even book elective caesareans on public holidays).
As further evidence, April 25, Anzac Day, is No 361, while February 6, Waitangi Day, is 362.
Apart from that cluster of public holidays, the second half of December is actually a fairly common time to be born. It’s 40 weeks after the beginning of autumn, after all, as the weather starts to get cooler and the days to get shorter.
Overall, the least likely month in which to be born is June.