Coming in late summer — human baby season

There is definitely a seasonality to human births, writes Beth Skwarecki at Double X Science. The complicated bit is that human baby season isn't necessarily the same (or as strongly expressed) from place to place and culture to culture. In the United States, significantly more babies are born in July, August, and September. Meanwhile, in Europe, babies seem to make their way into the world in spring. So there's clearly a cultural component to this — but culture doesn't explain it, entirely. Skwarecki's piece explores a messy place where culture, genetics, and circadian rhythms intersect.


  1. I would like to see data from Asian countries, especially China.

    All of my friends who are Chinese and Taiwanese are born in April within a week or so, around 5 people. The spread is also generational since they range from age 25-55. Might be coincidence but it would be neat to find out if there a correlation. Maybe there are more births just past the Chinese Lunar New Year? 

    And..I was one of those boring Sept. birthday babies. :)

  2. It’s cold in winter.  There tend to be baby booms 9 months after a major power outage.

    Also, lots of people feel cuddly around Xmas.

  3. Damn, I misunderstood the meaning of the article title.  I thought that human babies would be in season soon; especially in late summer when their parents take them all over the damn place and let them run rampant. 

    I have a big enough oven to fit in a few at a time, and the leftovers make great soup.

  4.  In Finland there is definitely a seasonality to births. Harsh winters make the prospect of bundling your baby up and going out in the cold for a walk unappealing, so more babies tend to be born in the spring and summer. I’m not sure what the peak months are, but kids don’t like having a birthday during the summer vacation when schools and daycares are out and their friends are all away. I would guess June and July are not as popular as May and August. 

    1. Since when do the kids get any say in when they are born?

      I know my wife didn’t want to be 9 months pregnant in the heat of summer, but even the parents don’t get much of a say on exact dates or timing.

      I think your logic is a bit flawed.  Kids come from sex, which is the determining factor in births, not the temperature or availability of friends for birthday parties.  I’d change your logic to say that ‘harsh winters make the prospect of staying home and making nookie much more likely than in the summer, when it is possible to do other things – hence summer babies.

      1. No, I’m with jackie31337 on this one. I grew up in the Nordics myself and it’s the way of life to attempt to time your births – i.e. by timing your use of contraceptives. My mum always makes a point out of my brother and me being intentionally timed to be born late spring/early summer.
        Get a late autumn/early winter baby and you risk being stuck with your newborn baby indoors for weeks.

      2. You must live in the US, where there is national, state, and local antagonism against learning the basics of human sexuality and contraception.

        Believe it or not, it is quite possible to make a rational decision on when would be best to have children.

        edited to add: A summer baby (say, June) would be conceived around September. To “make nookie” in the middle of winter (say, January) without contraception could result in a baby around September. Guess I should have added “biology” to the list of subjects that people in the US are deficient in.

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