Do more babies come out on a full moon?
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.