Why are most kids born during July/August/September ?

[Tender Branson]

I've looked through monthly birth statistics of the US and Austria and in both countries the most kids are always born in either July, August or September.

http://www.cdc.gov/nchs/data/dvs/provisional_tables/Provisional_Table01_2010Dec.pdf

http://www.statistik.at/web_en/wcmsprod/groups/zd/documents/statueb/027679.pdf

What's the reason for this in your opinion ?

[Tender Branson]

Winter is cold.  Cold people tend to stay in and cuddle for warmth.  Cuddling leads to other things, like babies in July-September.

Now it would be interesting to see the monthly birth statistics of Florida, if this is the case there as well ...

[Tender Branson]

Interesting.

Even in the warm Florida, most births take place between July and September:

http://www.flpublichealth.com/VSBOOK/pdf/2009/Births.pdf

(page 35)

[Tender Branson]

Christmas and New Year are nine months before, too.

Does the trend hold in the Southern Hemisphere, where it's Summer in December/January?

Even in Australia, July-September are the months with the most births, says the ABS.