Science of Love, Sex, and Babies

Do more babies come out on a full moon?

Posted in news, pregnancy, science by jenapincott on January 12, 2011

Nature still has a subconscious sway over us, and labor brings out the inner animal. We know that circadian rhythms of night and day affect hormone levels, which in turn may trigger contractions. So it doesn’t surprise me when I hear midwives, nurses, and even doctors insist that more births occur on a full moon.

Their logic seems grounded: a full moon has a gravitational pull on amniotic fluid, just as it has on any other body of water. The pressure causes the sac to break, thereby triggering labor.

I’m not the only one who wanted to put this theory to the test. There are over a dozen studies published on labor and la lune (including here and here), totaling hundreds of thousands of spontaneous, non-induced births and hundreds of lunar cycles.

Alas, none have found any significant differences in the frequency of births, route of delivery, preterm delivery dates, or birth complications across the eight phases of the moon (or, for that matter, the weather). It’s a myth, albeit one that has only waxed and never waned – perhaps superstition causes us to see patterns where there are none.

I also found studies that show that contrary to common belief, psychiatric wards are not any busier during full moons than maternity wards. The moon doesn’t make us loonier or more likely to deliver. We do both all on our own.

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  1. […] This post was mentioned on Twitter by Psychology Feeds. Psychology Feeds said: Do more babies come out on a full moon?: Nature still has a subconscious sway over us, and labor brings out the … http://bit.ly/g8sW5g […]

  2. mrG said, on January 12, 2011 at 12:43 pm

    It would seem obvious, then, to look instead at the symmetric problems, ie, to study the observers. Could people be more aware of special-case events over the full moon? Could they be attuned to remembering anomalous events during the full moon? (there being one rather dominating cue for memory retrieval is illuminating the sky)

    One thing I find about Old Wives Tales … in order to become ‘old’ the wives by definition must have acquired at least some ecological validity over those who do not; in the name of Science, it behooves us to find it.

  3. MimiVermont said, on January 13, 2011 at 10:11 pm

    Should it also be inferred that the full moon doesn’t make children act looney? Or is that just an “old” teachers tale?

    • jenapincott said, on January 20, 2011 at 2:36 am

      just a teacher’s tale!


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