From high tides to crazy moods, the full moon is believed to cause a number of things.
As the full moon approaches, full-term pregnant women everywhere prepare hopefully to go into labour.
An old wives tale? Or something mysterious that we hear plenty about, but don’t yet understand.
Ask any birth workers, and chances are they’ll tell you birth numbers increase during the full moon period each month.
The moon has long been thought to have physical effects on human beings – especially women. The menstrual cycle, conception, and even fertility have been closely linked to the moon’s cycles.
Suicide, homicide, and emergency room admission rates all increase around the time of the full moon.
How does the full moon affect labour and childbirth?
The moon’s influence is called the lunar effect. It is widely believed if a woman is full-term around the time the moon is full, its gravitational pull can influence when she will go into labour,
Just as the moon’s pull affects the waters on earth, it is believed to affect the amniotic fluid in a pregnant woman’s womb.
If the amniotic sac is under pressure, it can rupture and contractions might begin.
Myth or fact?
Many midwives and doula will swear there is an increase in the number of births during the full moon. There are plenty of stories about maternity wards overflowing with labouring women when that time come around.
But there is no evidence to support such a phenomenon.
A study in the 1950s looked at a series of days where there were extremely high birth rates and attempted to link them to full moons, but no correlation was found.
Since then, many studies have looked for links between the full moon and increased numbers of births, without finding any correlation.
A 2001 study, from astronomer Daniel Caton, looked at 20 years of data from the National Center for Health Statistics, including almost 70 million US births. Again, no correlation was found between the full moon and births.
So why do we believe it?
If the connection between full moons and birth isn’t there, why is it so widely believed?
The only answer is that the belief has been around for a very, very long time. Many cultures around the world hold strong beliefs in the link between moon cycles and women’s fertility.
Folklore tends to stretch back forever and has the ring of truth about it, simply because it has been believed for so long.
Most of us wouldn’t think to argue with an established ‘truth’ – especially if people ‘in the know’, such as midwives and paramedics, back it up.
This is called cognitive bias, which means noticing only what supports a belief and ignoring all evidence to the contrary.
A midwife might only remember when her maternity ward was full during a full moon, and not remember other full moons when the ward was normal or empty.
With or without evidence, a well-established myth such as a full moon kicking off labour is harmless. But while the full moon might not speed up the arrival of your baby, a storm might.
There is some evidence to show changes in barometric pressure can cause labour to begin. So if the full moon fails you, an incoming storm might be just the thing. Either way, your baby will be born when she is ready.
You can read more about what starts labour off in our article, What Causes Labour To Start?