[OC] Updated heatmap of birthday distribution and estimated dates of conception: United States 1994 – 2014

Posted by MissingVanSushi

11 comments

  1. As pointed out to me by some kind Redditors yesterday, estimating conception to birth is calculated using 38 weeks, not 40. I’ve updated my data model accordingly.

    Thank you!

  2. Looks like people really try to avoid giving birth on July 4th, Christmas Eve/Day and New Year’s Eve/Day.
    9/11 also stands out as being noticably lower than the dates around it, probably more so in the 2002-2014 cohort.

    Valentine’s Day looks like a top pick to induce labor.

  3. Is there a theory for why early April is such a rollercoaster for conception? Above average in April 1-4, less than normal 5-8, then well above average for 9-11.

  4. Does this take into account induced births and c sections? That could be why major holidays see fewer births than otherwise expected.

  5. I have two cousins with Jan 1 as their birthday so I am wondering now if the stats are just different for other countries and americans like to induce labor if it looks like the kid will be born on a holiday.

  6. There are still different numbers of each day in the week in the window. Look at the dips on July 13/20/27.

  7. For this to be meaningful any “scheduled” births (planned c-sections, induced labors) need to be removed from the dataset since it seems like that’s enough to swamp other fluctuations.

  8. “Births also decrease on… February 29th”

    There’s 20 of every date in the dataset except Feb 29th, of which there are only 5. It stands to reason there would be fewer births on a date that comes up less often, assuming it was perfectly random, but it’s not so this is further exacerbated by people not wanting their child to have a Feb 29th birthday. This would have an additional rider effect on whatever the corresponding conception dates would be.

  9. As discussed previously, the birth date chart is very interesting, but the conception chart is not valid in a day-by-day basis.

  11. My first son was born on Father’s day. The day before was my sister’s birthday and also a certain president’s. Glad he held out past midnight. At 11:30PM I was like push honey push… but not THAT hard yet /s

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