The Skeptical Teacher

Musings of a science teacher & skeptic in an age of woo.

Posts Tagged ‘full’

More Media Fail and Silliness: Lunar Effect Babies

Posted by mattusmaximus on August 17, 2011

This week there’s been a story going around the media about a supposedly huge jump in births in a Sacramento hospital where “45 babies were delivered in 48 hours.”  Now that may or may not sound very unusual (it ends up it isn’t that strange – read on), but the really weird aspect of this is the claim made by the hospital officials with nary a skeptical thought:

“The human body is 80 percent water, after all. And, given that both menstruation and ovulation roughly follow a lunar cycle – occurring on a monthly basis – it doesn’t seem too far off to think that the moon could have a say in childbirth as well,” hospital officials said.

And, of course, the supposed mechanism for this “lunar effect”, as espoused by the hospital spokesman, is gravitational in nature:
According to the news release, the moon’s gravitational pull “can control a woman’s body” the same way the moon’s gravity controls tides.
*Cue spooky music…
Image courtesy of

First of all, the fact that 45 babies were born in 48 hours is not that significant.  Note the article states that there have been a total of 325,000 babies delivered at the hospital since 1937.  If you do the math, then this comes out to an average of about 12 babies per day – compared to the claim in the article (which basically averages out to about 22 or 23 babies in one day), this seems not very extraordinary because it shows that there was a weekend where the hospital had only double the average number of births!  100 times the average number of births would be statistically significant, but not 2 times the average.

Then there’s the stupid claim about the “lunar effect”.  Not only is this a bogus claim – click here to see why not – but it is also implausible from the standpoint of basic physics.  The hospital spokesman makes a common claim about the “lunar effect” being gravitational in nature, like the tidal effects on the Earth’s oceans.  However, if one takes a moment to work through the mathematics, this arguments falls apart pretty quickly.  For example, I perform the calculations for the tidal effects of the moon (whether it is full or not is irrelevant) on a person in my physics classes, and it ends up the tidal forces that act upon a person are stupendously small – about one-billionth the weight of a paperclip!  So whether or not you decide to wear a hat or use hair gel on any given day has more gravitational influence on you than does the tides from the moon!

That’s because the strength of the tidal forces that act on an object are proportional to the size of that object.  In the case of a large planet, like the Earth, the relative difference between gravity from one side of the planet to the other (this difference is the tide itself) is pretty big since the Earth is big.  But humans are so small on this size scale that the difference in gravity (tide) on us is miniscule.

So the next time you gaze upwards and see the full moon, appreciate it for all its beauty and wonder.  But don’t worry about it making you crazy; the failure of the media to accurately report science is a bigger threat of making you nuts 😉

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