Why More Babies Are Conceived in the Cold Winter Months

September is most common month for birthdays, and if you count backwards from there, you may think, oh yeah, holiday celebrations and alcohol, long nights and cold weather, sure. That's the conventional wisdom, but September is not the most common birth month in all places. Scientists believe there are more natural reasons for peaks in human births that depend on climate and daylight more than cultural practices. In animals, evolutionary forces insure that births peak at the time of year that helps babies to survive, such as when resources are plentiful. The same forces may be at work in humans.       

There is a clear pattern of births across latitude. Here in the U.S., states in the North have a birth peak in early summer (June-July), while states in the South experience a birth peak a few months later (October-November).

Globally, popular birthdays follow a similar pattern with peaks occurring earlier in the year the further north you get from the equator – for instance, Finland’s is in late April, while Jamaica’s is in November. And in the U.S., states further south, like Texas and Florida, experience birth peaks that are not only later in the year, but also more pronounced than those seen in the North.

These peaks may have to do with temperatures conducive to newborn survival, or possibly the threat of disease- while diseases evolve even faster in order to take advantage of victims. Anyhow, the seasonal effect of birth rates is lessening due to birth control and a disconnect from our natural environment. Read more about seasonal birth rates and the possible reasons behind them at Smithsonian.

(Image credit: Arteida MjESHTRI)


Comments (7)

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I've been around long enough to know that people will have sex, regularly if they can, no matter what the weather. The research on the seasonal births has to do with fertility, not behavior.
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Not only is that not true, nor funny, but it's a pretty bigoted description of life in Africa.

To start, in Tanzania with one of the highest rates of lion attacks, about 50 people die from lion attacks (I can't find solid numbers; https://en.wikipedia.org/wiki/Lion#Man-eating says about 37 per year in the 1990s), while 18K people die from traffic accidents.

The usual explanation is lack of education, especially for women, distrust of prophylactics, religious views (eg, the strong influence in Africa of the Catholic Church's fight against condom use), and the view that children will provide more help with the household chores. Yes, the Catholic Church is far more responsible than any fear of lions.
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I guess one could apply the same logic to hot regions too. Why do African peoples have so much children? Because amidst all the heat, malaria, lion attacks - having kids probably makes you feel better about your situation.
Pressure makes diamonds :)
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Sorry but advertising is fleeting too.

This argument has a "I think talkies are going to ruin pictures" quality to it. The internet cannot kill print media, that can only be done by stodgy old print workers that refuse to accept their medium is going to change.

Change, not die.
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I hear the statistic a lot, but I must admit, I'm curious to know where it comes from precisely.

In my experience (I don't work in marketing, but do work with science magazines) magazine sales aren't doing as badly as people presume. Shares in the overall market have divided, from what I've been told, but this is far from 'print is dead'.

What successful magazines are realising is that the web is a tool that augments what they do, not competes with it.

Every new medium that has come into being has been heralded as the 'death' of something. The grammophome heralded the death of local choirs; cinema the death of live theatre; television the death of cinema etc. And while they all evolved from the impact of competing tech, none of it disappeared.

Print will be around for a while yet, even if will necessarily involve a digital component.
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I think this is just nit picking and a petty "mine is better than yours" plea. Having said that I wouldn't mind if there were less ads on the internet. I think whats screwing up the internet is everywhere you look is full of ads. I would definitely support fewer ads on the net so it doesn't look like spam central.

Until then I have my popup blocker though.
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I stopped taking paper magazines and newspapers when I realised that they made for so much of my paper-waste while at the same time I could read most of the info just as easy on the internet- often wit the added benefit that you can react and see reactions from other readers right then and there if you feel the need to do so.

I now await the developments in the e-reading tech and those other comparable technologies. I see a bright future for magazines and newspapers in that field.
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